A recent camera purchase, a Canon Legria HF-R506 model, shoots in either AVCHD or MP4(user's choice), I've set mine to shoot in MP4. Yes, importation of the clips to PD(8 or 14) creates shadow files, but I've found them not to hamper my editing, even when the shadow files haven't yet fully generated(turned green). Upon completion of editing, my final render is to MPEG2. I stick with this file type as it's "familiar territory". My last major shoot-and-edit project was a trip to a tramway museum in the outer-southern-Sydney suburb of Loftus in January of this year. That's not going to mean anything to our American friends but Australians on this site, particularly those in NSW, will know the place I'm talking about. In England, there's a similar tramway museum in Crich(probably much bigger than that at Loftus). I shot over an hour's worth of material and it came together quite nicely. Edited in PD14 from MP4 files and rendered to MPEG2. As I edited some of the shadow files had fully generated, some had not, but it didn't stop me or slow down my editing.. I still have the MP4 raw video should I want to create a newer edit at some future stage(I often do re-edits, always working on improving things, bits that made it in to an earlier edit that should've been left out, bits that missed out on the earlier edit that should've been included... you know the drill).
Cheers!
Neil.