I have a bare Cutter 20mm board and I'll have to desolder an XR-E from a 3-up board, but I can check that fairly quick.
How quick. I’ve got 10 minutes before I go to work? 
Hell, I don't even need to desolder the XR-E to see that it'll work, holding them next to each other is enough. The MT-G is of course wider, but the spacing of contact-center pad-contact is exactly the same. A little of the MT-G2 will hang off each side but that shouldn't hurt anything.
It will work, but sinkpad doesn’t make copper XR-E boards (or aluminum XR-E, last time I checked), and if you were going to use an aluminum pcb, you might as well use their MTG pcb, since like all their pcbs, the center pad has no dielectric layer.
Ooops I didn’t check to see if they did a copper pcb (or not)! Sorry folks
I would like to recommend you reconsider your decision to go aluminum star versed direct copper mount. You have build an amazing host that could take the MTG2 to new levels. The aluminum sinkpad will hobble the potential of the light. When you look at this very big emitter, you will see that it would be easy to direct mount on a copper pedestal and then direct solder wires to the emitter.
I second that, because I think you’re capable, but also for my own curiosity and the good of the forum 
There’s a very easy way to reflow that mtg2 onto the pedestal - turn an aluminum ring w/ ID of the diagonal length of the MTG2 and OD that matches the ID of the pill recess. Set everything in place. heat it up. done.
If you want a potted 9A driver I’m happy to do it for you and I already have one ready to go - just tell me the dimension of the driver recess.
This makes it safer and longer lasting, so it is less risk if you use the same amps in.
and BRIGHTER :party:
I do have to warn you though, soldering wires to the LED is HARD once it's attached to a big chunk of copper.
I’ve done a couple xmls and I soldered the leads first
edit: and if you really want to be safe doing that, use a higher temp solder on the leads…
Really? I figured the heat to reflow would unsolder the wires if they were done first. On the MT-G2 I of course cleaned off and re-tinned the pads before mounting it, it was still a pain (and ugly, I like nice smoothly flowed solder, which this most definitely was not). :p
you have to be careful to put the emitter in place right before the heatsink goes below the solder melt temp, then cool it right away…so it can be tricky
but if you used a solder w/ higher melting point for the leads, it should be much easier….
also, w/ the mtg2, there’s enough room to get my 240W soldering gun at those solder points J) , so it might not even be necessary - especially if you do it before the heatsink has completely cooled
What about drilling the center pad for 5-6mm Dia solid copper. If centered in the heat sink, that could be drilled and soldered too. Or mill the heat sink with a 1.6mm high x 5mm Dia post as part of the sink and drop the pcb over that.
I tried to drill one of the Cutter PCBs to do the copper rod riveting thing and failed miserably. There's a layer of something under the pad that ate every drill bit that even got near it. I dissected it with a diamond file (regular file wouldn't touch it) and it seemed like a layer of ceramic. If so, heat transfer on those things has to be abysmal and just about anything else would be a huge improvement.
WOW. Talk about put the pressure on. I have a friendly banter going on with OL to push each other that may sound rude to others. But this? I feel humbled by the expectations off members here. This is really pushing my abilities. Thanks to members here my soldering has improved 10,000 percent but in others eyes is still horrible. The offer off nine amp drivers potted that I marvel at is very generous (I cant think off the right words). Thanks. Rufusbduck I like your thinking as I dont have access to a mill but could possibly do what you have suggested. If you all knew my reputation for wrecking electrical components you would understand my hesitation. I have the led and it cost 20 bucks. Do I risk trashing it with my none electrical abilities and drive it at nine amps? I have a five amp driver ready to go. The host is on its way from the good old USA. Decisions.
Thanks for all the input guys. I have just taken a couple off Bex and heading off for a Nanna nap.
I should have clarified….
That driver won’t push the MTG2 to nine amps, at least if you’re using 2 cells.
I tried it w/ two brand new MNKE IMR 26650s. If you scroll down through the pictures you’ll see tail current measurements.
Summary: 48 watts into the driver (at turn on with FULLY charged cells)
If the driver was 100% efficient the emitter would be getting about 7.3 amps.
It most certainly is NOT 100% efficient.
I doubt it is less than 50% efficient…but at 50%, the emitter would be getting just below 4 amps (lower Vf).
My best guess…is right in the middle of those….so 5.5 amps…
If you’re talking about the 3-18V, 5A driver, you’re going to get more like 3.5 - 4A at the emitter.
edit: which is still plenty - and it will still be brighter if you solder that right to some copper
Thanks for talking Chinese to me. I think what your saying that if a 5 amp driver was for a 3 to 4 volt led that delivering 6 volts to a led would drop the current of the driver at the led? Yes I do need help here. Thanks.
Its chinese to me, too - but yes.
I don’t know much about how they work…I just can relay what I’ve tested
It seems some buck drivers still deliver the same current, even with the higher Vf…but others don’t quite make it.
Some drivers, like that 3-18V 5A and the manafont 3T6 driver that we’re discussing in a current page 1 thread, are also designed for use with multiple LEDs in series…so maybe that’s why?
We need help. This is the driver I have. What will it do with a six volt MTG-2?