4C is a fantastic tint, a warmer neutral white, and a favourite to many.
No practical difference in beam profile and output between XP-L and XM-L, so save yourself some cash and go for the latter.
I would not trust Trustfire (pun!) batteries.
I would recommend Panasonic NCR18650PF. They are not protected (usually) but very good. Look here (should be same cell, just re-wrapped): Test of Keeppower IMR18650 2900mAh (Black) 2014
I bought them at Banggood.com because you can choose Netherland Direct Mail (really fast, good chance of avoiding customs)
First of all you need to know that these SolarStorm X2's have been cloned to death and the majority of the ones out there today have no "pills" and the emitters simply rest on a "lip" (i.e. terrible thermal path). But besides that, why change out the LEDs? If for tint, fine, but I don't understand otherwise. I have a SS X3 which I swapped in XM-L2 T5 5B1's in (4000k) and love it! The SS X3 throws a ton of light, but at the cost of running down your battery (not awful, but not great runtime).
For a battery, there is a seller on Ebay "Hunk Lee" (I think) that sells custom made Panasonic battery packs with connectors (which can be custom requested too) which come highly recommended over at MTBR. Or, you can do what I did and buy a Pannova battery case and use your own protected (or unprotected) 18650's. The Pannova case is available only a few places (probably could find it on Aliexpress) like Ebay, DX, and KD. Lots of info on the Pannova, and the SS X2, over at MTBR too.
Here's a beamshot of my SS X3 with the 5B1's swapped in. I used to like the 4C, but I find the 5B1 so much better!
-Garry
Thanks for all the answers!
I hoped, that the clones are good enough to be modded, but with the famous chinese cooling-hole under the LED it’s useless.
The X3 looks kinda good!
I would never Use only 4C bins in that.
I have a lot of Flashlights with 4C - for a bikelight too warm.
I have one SK98 with a XM-L2 3C LED (4750-5000K) - I think, thats what I want.
But I will take a look at the 5B1. Maybe it will be a mixture of two 5B1 and one 3C.
Where to buy a good one? I have no problem in modding things, but I don’t have a drilling machine or lathe for big materials, only small <8mm 
If I look at the price of that case… I think I will go for 4 18650 with a glove over it or so. I don’t want to ride in bad weather or downhill or smth, just a little bit biking and enjoying my “little bit brighter that others”-bike light 
What about that raw 4-Pack of green 18650? (click)
Not sure if that pack is reliable or not. They look like Panasonic cells in the photos, but not specified. Hunk Lee's are spec'd to be Panasonics and users confirm they get exactly what they expect.
-Garry
I found Hunk Lees store, too - but it shows “0 results for bike battery pack” - and the hole Shop is empty (“0 results found in all categories” + “This Store currently has 0 listings. You can come back later or check other Stores.”)
I don’t know, whats wrong with it - maybe he doesn’t ship to Germany?
Edit:
Maybe rip one of these apart:
http://www.aliexpress.com/item/-/2011201472.html
They seem to be very good, especially for the price.
-> ?
Or just use this and change the Voltage from 5V to 8.4V with a boost module…
I’m slightly confused: you say the 4C tint is too warm for bike use but you want to try a 5B1 bin? You realize the 5B is warmer than the 4C? Lol. That being said, I have a single 5C1 noctigon bike light and really love the tint. The warmer tints are better in rain/wet roads.
EDIT it might be 5B1 tint. Checking now. 5D2
Hmm . . . Perhaps no shipping to Germany. I see a bunch of listings. Why not just do the Pannova case? It'll even run on just 2 cells. A good neutral white will bring out the details much better.
-Garry
EDIT - 1/19/2017 - Came across this post and want to revise to say that I believe these photos were taken during a time that I was using the wrong white balance setting and all my pics came out way too "cool white" looking! The 5B1 should look way warmer than in this photo!
I was taking beamshot pics last night and got a photo to compare my SSX3 with T5B1 tint (on medium output level BTW), and my Convoy S2 with T6 4C tint (@ 2.1A):
SSX3 T5B1:
Convoy S2 with T6 4C:
Mouse Out=SSX3 T5B1, Mouse Over=Convoy S2 with T6 4C
Same mouse over, but with the SSX3 on Low:
Tough comparison since the S2 looks like a thrower compared to the X3! I really need to do the comparison with similar sized lights.
-Garry
Sadly, there are a very few Pannovo battery case seller now. Not sure why SS discontinued their case too.
Thank you for the Pictures!
So, what about that:
Good value or is there something better for not much more $?
Does FT ship LiIons to Germany?
Is there a must-have mod for the X3?
Thanks!
Felix
Those Sanyos are the 4.3v ones. Charging to 4.2v won't give the rated capacity (see HKJ's test and the 18650 comparator), though they will work ok. I think the good ol' 2600mAh Sanyos turn out to be a better deal. Actually Banggood still has the 4 pack of protected Samsungs 2600's for $18.65 - best bang for the buck I know of. They have been proven to be real Samsungs too. I know nothing about the shipping of Li-Ions right now (haven't been following posts on it).
I've seen the X3 for a little less on Ebay, though with "economy shipping" which generally means no tracking# I believe.
The only thing you "must" do is open up the front and check for thermal paste under the emitters, check for pills, and add thermal paste (under emitters and at pill seats).
Like so:
(Sorry, I don't have a great pic of it.)
Link to my SSX3 PhotoBucket Album.
-Garry
Thanks for the bat-link!
bought 2 4 packs for €27.30
The light itself at ebay costs ~18€, the waterproof bat case ~12€.
So all topgether around 60€ for a good light and waterproof battery pack.
So, tonight I’m going to watch for some good XM-Ls 
Sounds great! Glad I could help.
-Garry
Hi!
Just one more question:
Am I right about the size of the XM-L board: 16mm?
I have some 4Cs here and will buy some 3B and 3C for testing.
Is a driver change recommended or possible, or is the built in driver just fine?
I purchased a cheap clone from Banggood SKU131517
This is what I found when stripped down
So I had a couple od Alu heatsinks made, these are a tight fit, going to use a little thermal paste too when building.
Planning on replacing the LEDs with warmer Tints on copper, just waiting for James to return from his holiday to purchase from his sale thread - FS: XML2 XPG2 XPL XPL HI MTG2 XHP50/70 Components + Extras inc. mod service RE-DESIGNED
Most likely will be 16mm boards, but sometimes it's a custom single board the shape of that entire opening. Driver will likely be fine. Not that easy to replace, though it can likely be resistor modded.
-Garry
Alright, everything done.
Bat case ordered, batteries, 2* XM-L2 3B, 2* XM-L 3C, one XM-L2 4C (I have at least one of it here) and the X3.
All together not really cheap, but at least I got something good. Hopefully
Maybe I have the chance to mod the X3 like Essexman - I have enough Aluminum, just got to get to a bigger lathe than I have usually access to.
Even if all fails, I got 8 more 18650. I only have 14 right now
Thanks to everyone, especially to you, Garry!
When you get your X3 can you post photos of your driver, we could compare drivers and see if they can be improved/boosted.?
Sure thing!
If I don’t forget, I’ll make a little review before and after.
But I know myself too good.
I just got this light: http://www.aliexpress.com/item/New-sale-2000Lm-XM-L2-Waterproof-Flashlight-Torch-5-modes-free-shipping-T6/1736634921.html
And moddet it with the good 2,8A Nanjg 3 Mode driver and some heat transfer paste. Now it is a good light, but I can’t make a review on that, so it’s going to be a not knowed flashlight in here