EF-S on FF sounds cheap and not very smart APS-H is a better reason for such discussion.
IMHO, Canon should have made 1D bodies compatible with EF-S lenses, because now they are selling a pro body that can't shoot UWA with OEM lenses. 14mm x1.3 ~ 18mm, 16mm x1.3 ~ 21mm.
Big mistake, Canon.
The 1D bodies weren't made for shooting UWA; they're for shooting action/wildlife at tele and super-telephoto focal lengths, hence the 1.3x crop and higher frame rates. A pro or serious amateur who needs to shoot UWA, is going to use one of the full frame (1Ds or 5D) bodies.