Followup:   Should be sorted now with a smallish AK2M4 care package.  The gearbox shell continues to surprise, it seems less Chinesiumy than most, and was quite resistant to being radiused. What a bizarre decision to fit crappy plastic bushings with a decent (but unradiused) shell, gears and piston.   The shell also has some helpfully-annoying posts intended to keep the very thin stock wiring in place that need removed in order to use anything chonkier.   As reported by other owners, the trigger can feel notchy in semi. This is down to the safety lever that blocks the trigger staying very slightly raised on (or around) semi. It should wear down, or just nudge the selector a tiny fraction more towards auto.   As an aside for the "wut spring 2 get maxumin powar?" question, with the stock spring, plus a new bearing guide, o-ring nozzle, Specna rotary hop (I think), Maple Leaf bucking and a ~365mm 6.00mm[*] barrel, the no-hop power with 0.28g went from <1J  to >1.25J (adding some hop brings it under 1.2J, although I may not get under 1.13J with properly 0.2g for indoor  ).  Air seal is king.   But good God, it's time consuming to work on, with so much take-down and put-back to do anything. I nearly wept when I realised that I'd put the gearbox back for the twentieth time before fitting the hop and barrel, despite repeating to myself "Put them back as a unit" over and over.   [*] An XT from AK2M4, labelled as 6.02mm from a sample batch that came out under-sized and was sold as such for a bargain price - it is indeed a proper tite-boi.  

Maaaybe. Mine pets its lip with 11.1V, a Big Dragon M160 and an M120 spring in a DMR build.  Remove any of those factors (7.4V, or stock motor, or M90/M100-ish spring) and it'll cope. They're poor units though, and clearly only there to tick the "has mosfet" box.

I would put money on it that the X-ASR will shit itself with a motor that pulls any more amps than the stock one.   Allegedly the X-ASR V2 has resolved the issue - at the expense of removing the reverse polarity protection that was present in the V1.