I guess this'd be a nice thing to have. If you don't have the new sounds, you can get them through the full build20 install, or if someone is nice enough to post their sound folder here, you can grab that as well and stick in in /pball.
Anyway, for me the new sounds don't seem to fit with the old ones. That's not entirely bad, so long as eventually all of the guns' sounds are updated. Specifically, the new sounds sound much 'harder' than the old ones, and not just because they're higher-quality. I'm not entirely sure what that means.
The new splat sounds are a bit high-pitched for my tastes, but that's just me.
Aaaand all of the new gun sounds seem to be about %50 too loud, compared directly to the other guns' sounds.