Lots of plastic
Comes with 3 mags, holds 2 extra mags in stock
locking non-reciprocating charging handle (but sometimes it doesn’t lock?)
Folding to the side
vs Sub2000
More bulky even though it’s mostly the same volume
FPC Can mount an optic without doing anything dumb
FPC Can’t really take a scope
FPC uses M&P mags, Sub2k uses Glock or others
Charging handle and bolt release is arguably worse than sub2k