I’m looking for some sort of workaround, for example, 2 playlists:

ToPhoneAsMp3
ToPhoneALAC

Then auto sync disabled and in the auto-convert settings I switch between the playlists and enable/disable the convert rule appropriately.

The downside I see to this, other than the extra hassle, would be not having tracks auto removed from the phone when I remove them the playlist.

I’m holding out for an even more creative solution.

This is not possible. You can only set Auto-Conversion rules by file type/characteristics, not by tag or Playlist.

Most of my music library is stored as FLAC, I sync a “phone” playlist to my iPhone.

I’d like to be able to nominate which files should be auto-converted to mp3 and which to Apple Lossless.

In an ideal world all FLAC files would auto-convert to a lossless format but my phone storage is limited, so I want to maintain either a separate playlist for each auto-convert format or store a tag on tracks to use as a condition for the auto-convert format.

I have MM4 & MM5 Gold, from what I can tell there is no way to configure this condition into the auto convert, does anyone have any ideas/suggestions?