With all respect, I wouldn't let myself get lured by the "sex appeal" of an MP-5 clone if you intend to use the firearm as a self-defense or SHTF weapon.
Full-auto subguns really rely on hitting the target with multiple projectiles to get reliable stopping power, much like shotguns. A semi-only subgun clone is still probably a better weapon than a pistol in the same caliber, though (easier to aim quickly, better rapid-fire control).
Even if I had a full-auto MP-5, I would prefer a semi-auto rifle for home defense or SHTF instead. That's not sour grapes or envy speaking; it's because rifles have considerably better stopping power and can penetrate heavy body armor, whereas the MP-5 can't.
Having said all that, the fact that citizens can't legally buy new full-auto weapons (1986 law) is probably the single most unconstitutional gun law on the books today. It's not that full-auto is that useful (from shoulder-fired rifles, it's almost always inferior to rapid semi-auto) -- it's the principle at stake. We should work on getting it repealed. The fact that the NRA is silent on this issue really shows their true colors. Same with the "pro-gun" Republicans.
