I've been running a Gen 3 CQBR for a while now. Build quality is good. Internals are strong (nothing you would need to swap out straight away), with very good compression. Everything inside the shell is standard v2 stuff, barring the cylinder), so upgrading should be straight forward. Hop is very stable, rarely needs adjusting once set for you brand of BBs. Just swapped out the spring for a stronger one (the stock one, by my reckoning, was an M95).
I quite like the blowback feature - its not really recoil, more for visual and sonic effect. It does make gearbox teardown a little more of a a pain tho. The ability to disengage the anti-reversal latch with the forward assist (or from the side of the gearbox) is a nice feature. Spring will last longer and makes taking the gearbox apart less fraught.
As for the MOSFET, I did have a discussion with the blokes at Pro Airsoft Supplies and there have been reports of returns due to mosfet failures (possibly being run on 11.1 lipos but I cant confirm that). I've been running mine on 9.9v life batteries and had no problems so far (must have put 4-5k rounds thru it so far).
Overall I would recommend if you are looking for something that works well out the box but has lots of upgrade potential down the line.