I think it's extremely difficult to keep perspective on the tunes if you've written, played on, tracked & produced them yourself...so, I always try to hire a mixer, especially if I'm the singer. For some reason, if i'm not the singer, i'm way more comfortable mixing it...
Even if you don't have the dough, and the first few hundred records have to go towards paying back the person you hired to mix, I find that it's a worthwhile expense.
Some people can wear all the hats...Ken Andrews in particular...i love all his work and it keeps getting better...
It would be nice to have Chris Walla chime in, particularly 'cause his band is really hitting its stride both artistically and commercially and he kind of checked out early on the thread documenting the making of the new record, which turned out really well...