I was thinking about loosening the springs on my vintage trem to turn it into a floating trem, but what are the downsides? People seem to think it's a bad idea, but I don't know why. Has anybody else tried it?
I have. You can't loosen it too much. It is VERY hard to get it JUST right so it actually sustains tunning. Too loose and it gets impossable to tune, period. Too tight, and, whell, it's nto much of a floating trem eh?

Oh, and be prepared to tune your guitar for an hour straight intially....