OK, I try!
I have photo about the selective fire version:
So don't have to make it fully electric, mechanic trigger system is much more reliable. Hence less ergonomic... and don't know where should be the safety...
Trigger response is a difficult question. With fully electric system I can only shoot slow in semi auto. With mechanical trigger wire... I don't know. With single auto FET??? And what happens if you switch between single auto FET, and electrical only full auto???
The micro switch of the trigger is the weakest point of my one, it went wrong two times...
