Good points. With regard to the M3U feature, I am most concerned with the issue of the first upload. That's where most of the work is required. M3U playlist utilisation for the first upload would save tons of time. For subsequent uploads I would use the "standard" Emplode procedure (manual track assignment). Once I've established the base playlist organisation using M3U files I expect that changes to the playlist configuration would be relatively painless. I would only be either rearranging the playlists or adding new tracks from recently purchased CDs. This is relatively low volume work.
So if the M3U is only valid for the first upload, that would be fine.
Regards
Lester