Maiden, you probably had those issues with deft cause you sanded so quickly. usually after 3-4 weeks of sitting its good enough to sand and buff without case damage (in my experience). I agree with the stew mac clear though. Its hard, and cures a lot faster. I have too look into the behlen now though sounds interesting.
Oh yeah, I agree with maiden, Scuff the finish. Hes probably right about it flashing and not letting it off gas. I did this the first time I used deft when I coated to heavy. After I sanded it the smell went away after a couple days. (by this I mean I couldn't smell the deft unless I put my nose right next to the guitar. Instead of smelling it right away when I walked into my makeshift spray booth at the time.