Very familiar with the site. Wet mostly. I have two MC kittens which also get this brand of wet with some dry on the side (would prefer no dry but I don't want the kittens to get in the habit of inhaling wet when fed only 2 / day) .Are you using dry or wet foods?
And are you familiar with http://www.ibdkitties.net? This is probably the best resource out there for people with IBD kitties. The site owner has worked with vets that specialize in IBD for all the information up there.
And your vet is incorrect about liver. It is very individual per cat. Many people on this site switched to raw food for their cats when nothing else helped resolve their kitties' IBD and liver is a critical component of a raw food diet - and their cats are doing great. So liver is definitely not "by definition" a problem for cats with IBD.