Just a few minor things, the mag well is tighter than the UMP/USC so mag changes are a bit slower, no last round BHO(although an MP5/40 may have one), barrel changes are a bitch.Hey Jeff, I think I am gonna trade in my UMP for a MP5-40. I like the LOP better on the MP series. Plus I will have a couple thousand bucks in my pocket to spare. You seem pretty happy with yours. Is there any dislikes?