Once and for All seems to have been a fairly short-lived band from Cerritos, CA. They recorded two demos (which I've never heard) in January of 1989 and this 7"—tracked at Westbeach Recorders with Brett Gurewitz of Bad Religion and Epitaph Records—in December of 1989, released the following year by the mighty Nemesis Records.
Thinking Man's World must be one of the funkiest hardcore records I've ever encountered. Loaded with nonstop slap bass and hip-hop-inspired vocals, it's basically borderline funk metal from a band that just happened to have been more attached to the hardcore scene. I mean, shit, the second song is even a cover of Edwin Starr's "War"!? Searching around online, one can find some rather harsh words for this EP, but I'm a total sucker for this kind of stuff, so I really get a kick out of it.
I'd love to know if any of these guys moved on to other projects after the fact, but they were never credited with more than first names. The demos simply cite Byron (bass), Jeff (drums), Rob (vocals), and Andy (guitar); while the 7" doesn't even credit instruments, simply: Mike • Jeff • Rob • Andy. So, I'm guessing Mike replaced Byron on bass at some point, but who knows!?
And, hey, several cheap copies are available via Discogs (on clear vinyl, no less) if you're interested...