compression is relative, but i have to agree that a good compressor can do wonders for your live sound. it's just that lately i've been leaning towards a more open sound, so it's either compressors with a variable blend or no compression at all for me.
i'd like to get something that warms up my tone first, though. sansamp, some sort of low-gain overdrive or a nice outboard preamp if i'm running a passive bass. some of the best tones i've gotten were from a passive p-bass run through an aguilar outboard preamp straight to board.