Full-auto fire is the sound of your wallet emptying. These things use ammo FAST. I blew through 100 rounds of 9mm out of a rented Uzi in about two minutes. That was range ammo, $11 a box.
That said, I might look into the .22LR beltfeds if the cost was lower, or maybe a STEN to tear up the sandpit once in a while. At the ranges and in the circumstances I am likely to need to defend myself FA anything wouldn't do me much good and possibly create more problems. Every bullet you shoot has a lawyer attached to it and letting loose 30 of them in a short period of time sounds like a recipe for civil liability to me, since I live in the city.
If the regulation did go away I think we would primarily see a huge drop in prices on AK's because they would not need to be remade. That would be the only other FA arm I would consider, but for the reasons of cost rather than FA capability.