Just flashed it, and it booted just fine at least! Now I've gotta make a backup of this drive, stick the new one in, and try to format it.
edit: Just formatted it, and it shows 191.998.607.360 free on F, so I think it worked! Woo hoo! I copied C and E back over successfully, and now I'm on to the big stuff--apps, emulators, games, and videos. About 160 gigs in all, I think. It's running pretty steady at around 7000-8000k.
Would it be OK to run Avalaunch on this BIOS, or should I stick with Evox (older version--I hate 3935)?