No expert on either, but I do know the bbls are not interchangeable.Since the aftermarket folks carry them separately in the catalogs, they're not interchangeable with each other, either.
Lots of folks that do lots of shooting with one or two loads like the trap folks use the 1100. The 11-87 is easier to switch loads on. IMO.
Early 11-87s were plagued with a number of glitches, now seemingly rectified. The 1100 just keeps on going like that little pink drum beating rabbit...