They are great little guns, I have mine in an SRU bullpup kit and it hasn't missed a beat in 4 years.
Lightweight snappy and pretty reliable you can't really go wrong, only the mags are rather expensive and the older ones were heavy.
I have an FG nozzle on both my ak105 and m4. They have both worked extremely well and are actually relatively consistent in output (compared to an NPAS etc)