Thank you my good man!
Love my MPP-1 but the only thing I dislike is that its much brighter on 2 x CR123 than 1 X 18650 or 2 x 18650. It pulls around 1.1A with 2 X CR123, around .8A on 1 X 18650, and around .6A on 2 X 18650.
You are _the_ man . . .
thankuuuuthankyouverymuchFoy
I know I don't really get it either. I bought an L2 Extension tube and everything so I could run 2x 18650 and avoid buying CR123s. Oh well.
Does the Solarforce MPP-1 have the new XR-E R2 emitter that can be driven to 1.8 - 2A? Most websites state that the MPP-1 uses a CREE XR-E (WC-R2) LED. According to this thread (https://budgetlightforum.com/t/-/4992) the Cree 7090 XR-E R2 WG can be driven to 2A. What's the difference between the WC and WG?
If the MPP-1 indeed has the superior R2 LED, then one can just do a driver swop-out to make the best thrower ever! 
It seems the WC and WG are just different tints, with the WG being warmer.
So does this mean that we can slot in a 2A/1A/0.5A driver in the MPP-1?
I've often wondered if it could be driven harder and if so, what kind of performance gain could be had. As it is, it's an incredible thrower but it throws a comparatively small amount of light.
Still; every time I use it I have new respect for the XR-E.
surfacebrightnessFoy
Foy, how does the MPP-1 compare to the throw of the M8?
It out throws the M8. It's not as bright of course, but it does have more reach.
Foy
I have been playing around with XREs lately and they pull around 1.7 amps on direct drive. This light is limited to 1 amp which is the safe number for XREs but by bumping this light up to 1.7 amps there will be a visible gain in output. It seams like a shame not to max it out with that awesome reflector.
Beautiful workmanship!
I'm using an L2P and an extension tube for 2 x 18650 use but the truth is; the XR-E is what it is. It's a great thrower but despite the XR-E's bright surface, it is a very small die that can handle only so much current.
Foy
Try running 2 X CR123.
I would definitely make them replace it. The reflector on mine is so perfect it looks like a piece of art. Completely unacceptable and as I have said before; the famous Solarforce quality has been surprisingly inconsistent lately.
I have a sand, old style L2 I received a couple of months ago that arrived with curlys of aluminum still wrapped around the tail cap threads. Right now, the tail cap will not come off at all - like it is welded on.
Solarforce better get it together . . . hope you get it resolved.
Foy
Sorry to hear that man, I'm also about to pull the trigger on the MPP-1, but not if their quality is down the drain! 
Where did you order from?
Hope you get it sorted!
I finally decided to pull the trigger and get the Solarforce Masterpiece Pro-1. My unit arrived in perfect condition, no anodizing chips, perfectly centered XR-E, and I'm very happy. I don't have any real uses for it, but I do love it, and keeps finding excuses to fire up the MPP-1. The only thing which I'm not happy with is that on a wall the flood of the beam is quite ringy (but I knew that beforehand), and you need 6v+ to properly drive it (which I also knew beforehand).
I have got a question about the MPP-1 driver though. I've posted my question here: https://budgetlightforum.com/t/-/5819#comment-158981, but I think it's worth posting in this thread as well:
So let me know if I understand this correct...
Lets assume the buck driver in the MPP-1 needs 1v more than the XR-E forward voltage (3.7v) to fully regulate the light. That would mean that you have to drive the MPP-1 with more than 3.7 + 1 = 4.7v. If the input volt is less than 4.7, the light will go into direct drive. One 18650 minus the driver, can supply between 3.3 and 3.5v to the led, which according to the datasheet will draw 350 - 700mA.
However, if we supply the MPP-1 with more than 4.7V we go into regulated mode. When coupled with 2 x CR123 we get a reading of 1.15A (according to motodeficient), which equates to 1.15A x 6V = 6.9W. The same happens when coupled with 2 x 18650 we get a reading of 0.8-0.9A (what I've observed), which equates to 0.8A x 8.4V = 6.72W
So this means the input watt is ~ 6.9W and if we assume a 90% efficiency, the output watt should be ~ 6.2W. Since the forward voltage of the XR-E R2 is 3.7v, the current going the XR-E is 6.2 / 3.7 = 1.675A And its at this point that I'm really confused, because everyone always say Solarforce underdrives the MPP-1 and that the Dereelight 3SM driver is better for XR-E R2's. Am I missing something? Even in this post https://budgetlightforum.com/t/-/4992#comment-94538 if you assume that the forward voltage is 3.8v at 6.2W, the current would still be 1.63A
Please correct me where I'm wrong, because I just ordered a 3 - 18V input and 1.6A output driver for my MPP-1 and after thinking a bit about it, there would be absolutely no gain 
Well the cell voltages drop fairly quick by the current run through them, so I think you should take 2x18650 as 7.6v and 2xcr123 as 5.4v at most. %90 efficiency is close but may not be the exact value as I would account an efficiency just over %80 more realistic. Still, with these values I calculate around 1.2-1.3A through the led and I believe this isn't a bad rate for an XRE. Emitter efficiency drops fast over 1A. You would only gain a few tens of lumens over this value, I think.
I thought perhaps an updated base-line tail cap draw might be helpful . . .
| 1 x AW/IMR | 1.0 - 1.07 amp |
| 2 x Tenergy unprotected 18650/2600 | .75 (1.50 to emitter) |
| 3 x Panasonic unprotected 18650/2350 | .51 (1.53 to emitter) |
| 4 x Panasonic unprotected 18650/2350 | .39 (1.56 to emitter) |
| 2 x TrustFire flame protected 16340/880 | .80 (1.60 to emitter) |
| 2 x Eveready CR123 3.0 volt primaries | 1.16 - 1.18 (2.32 - 2.36 to emitter) |
| 4 x Eveready CR123 3.0 volt primaries | .54 (2.16 to emitter) |
| 2 x Tenergy LiFeP04 3.2 volt | 1.03 (2.06 to emitter) |
Just wanted to make sure we're all on the same page about how much current the emitter is actually getting. Or, maybe you guys are all up to speed and Foy just re-invented the light bulb.
Foy
Thanks for the measurements Foy! Are those calculated or measured amps going to the emitter?
Kokopelli, I read in a thread over at CPF that a person reported gaining 1-2% lux when going from a stock MPP-1 with 2 x 18650 to a 4.2v 1.4A driver, so I recon the stock MPP-1 will supply 1.3 - 1.4A to the emitter
Well, I've already ordered a replacement driver, I might as well do a tmp swop out and take some beamshots to compare