All things considered,(Weight, RPM, cartridge, etc.)if you were a soldier, and you had to bring one of these SMGs/PDWs with you on a special operation, What would it be?
-FN P90
-HK MP7
-HK MP5
-BT MP9(Either in 9mm or 6.5X25mm)
As weird as it might sound, the Uzi either a full size or mini. It's a very space eifficient and quite a reliable design.
I finally had the chance to handle a MP5 SMG a while back...NOTHING about it fits me. Even one with extended controls was uncomfortable. It seems liked selector is just too short. It's also needlessly complicated and a pain clean.
As far as 5.7 or 4.6 and body armor...the threat is either from a developing country (no armor) or will be wearing armor with ceramic inserts that will easily stop either round. I'll take a rifle in the later scenerio and stick with the 9mm in the former.
It makes me sad that the "H&K Slap" is so anti-southpaw, otherwise I'd be all over the MP5. The PS90 is fun to shoot, so that would be my choice. I haven't shot an Uzi, so I can't say one way or the other what they're like.