M85 FCE can only import SOME avchd. For instance, I've been trying since last fall to get it to import AVCHD from my brand spanking new Panasonic HDC SD100. It can't. Period. Final Cut Pro 6.05 can and iMovie '08 can (though I'm having audio sync problems with the iMovie and it converts 24p to 29.97 when it imports).
Anyway, I hope Apple updates FCE soon, but until then Voltaic is your best bet. MPEG Streamclip won't import mts files either, by the way.
(Version 1.8.1)