I've been using the nightly builds of 1.1 since November. You do get occasional glitches (like disappearing menu bar in the latest), but it's mostly fast and stable.
at current stage, try avoid trunk nightly build, mozilla is on the process of switching to cairo, trunk build is very unstable now(for firefox, seamonkey, camino, thunderbird too). go for 1.1 nightly build instead until the transition ends.