hi mr ed,
the actual version 6.0.3. seems to have a problem with burning the iso-image file from an xbox-image:
whenever you select an xbox iso-file to be burned in image-mode, its format will be recognized by toast like auto-detect format is turned on, so there´s no chance to get down to the "pregap-dialogue" (although auto-detect fomat is unchecked!). i did not try out yet what happens if you burn it nevertheless, because i bet this would produce a real fine coaster (but any hints that teach me i´m wrong are more than welcome).
perhaps its just a bug in the actual update as i had no problems on that with toast 6´ earlier version (6.0.1). unfortunately 6.0.1 has some lacks (buffer underrun support missing, timecode pretty much inexact,... ) so an update to 6.0.3 would be a really good idea.
i have both versions in my applications folder: 5.2.1 to do my xbox backups (works fantastic under panther) and 6.0.3 for burning all other kind of things. the new toast 6 has hell of a lot new features that i really dont like to miss any more (like cue-bin burning, svcd support, LAN-burning and much more)
to cut it short: i really recommend an update to 6.0.3 but better keep your version 5 too.
hope that helped