if it were me, I'd wait until Adam gets the run of Dakota Tactical MP5/40's in or call Ghillie and see if he can build one for you........either of those options yields you better odds at having a nice gun vs a Franken gun
I have a PCS built 5/40 that came with my sear purchase.
I had some ejection issues which seem to get better by shimming the pack. I seem to be "inbetween" locking pieces as the 180grs I prefer (WWB & UMC) seem to overfunction a bit with the 24lp. Been using the 26lp of late with decent results (1 or 2 failure to eject every 100 rds or so)
In a word shooting the gun FA is FUN
Was looking at the Vector build for a backup or spare. German build kits will one day be no more I suspect. No doubt Dakota's or PCS would be better. I guess Vector realized the need for German/HK parts to make these guns work reliably.