but tim, let's also be fair about the image quality of some of the ef-s mounts
i have 2, the 10-22 and the 17-55 f2.8 ISm, these seem to me to be 2 of the best lenses i currently own, esp the 17-55, more than 1 person has web reviewed this lens and stated that they feel it's an L quality image maker, just not an L in name or build, 90% of my european trip photos were with the 17-55
so even though i have just made the move to full frame 5d, i'll be keeping my xti as a backup and to use for the reach crop factor on my bird lenses.my basic motivation for the 5d purchase was that i do a fair amount of low/available light stuff, particularly outdoor music festivals, and i felt i really could make a quality increase with full frame for these conditions
and just to throw it out there, i have long owned a number of L grade lenses, i always felt i would eventually make the move to full frame as it became more affordable and market driven, plus i have been a firm believer in the adage that good glass, properly cared for always stays good