I got a bunch more of 404's on the way and just got in XPL2 V5 4000K LED's. Might be updating the 4X SRK clone (with the BLF Q8 driver) with those LED's, and the 404 FET. Would be interesting... I measured 7.8A at the tail on a fully modded ThorFire JM07 with the new XPL2 V5 installed, running Narsil of course 
. It measured over 1,800 lumens @30 secs in a nice 4000K tint. In a 4X SRK, it might do close to 25A - pretty crazy. In our BLF Q8 proto, bet those LED's would do 28A easy, maybe 6,700 lumens.
The XPL2's have a low, efficient Vf, making it much easier to get higher amps, and they seem to be able to handle it well, with peak output at about 10A, shown here. Main complaint is the tint of the beam, with a more yellowish halo around the hot spot. Really want to see how it will look in a multi-LED light.