That's a good point, Mark. I use ModelConverter X for a lot of scenery work, but I've never tried it as a repainting aid. Is there a way to show various liveries of an aircraft MDL, though? I just tried in my copy, but couldn't see any option for that.
In the newest beta version you can select the livery without reloading or modifying the filestructure!
Theres a note on the betas and where to get it in the download thread here:
http://www.fsdeveloper.com/forum/forumdisplay.php?f=87
Cheers,
Mark