I'm pretty sure it was QOTSA who did the split with Beaver. It had "These Aren't The Droids You're Looking For" and "The Bronze" on it, if I remember correctly.
The only subpar Kyuss release I can think of was the best-of, "Muchas Gracias." It didn't even offer subpar music ... all the songs on it are obviously pretty damn awesome, particularly the otherwise-unreleased opening track "Un Sandpiper." It was just a poorly constructed compilation. It was pretty much just B-sides, unreleased tracks, and live recordings, with a few classics in between. It couldn't decide whether it wanted to be a "B-sides and rarities" disc or a "best-of" disc, and it ended up not really serving either purpose very well.
It's still worth your money, though, just for "Un Sandpiper," "Shine," "A Day Early and a Dollar Extra," and "Mudfly."