Our Ped would say it's becoming a habit/self soother for your baby to have the bottle. Although i don't think a 9 mo should be expected to sleep 8+ hours straight w/no bottle, I do think that three bottles during the night is more then he prob needs.
Our daughter is 15 mo and still takes one bottle-sometimes 2 during the night and I KNOW it's a soother for her. If I hear her I turn down the monitor and she'll cry for about 20 minutes and fall back asleep, but if Daddy hears her and I don't he jumps out of bed and gives her a bottle. Gee...wonder why she still thinks she needs it...:)
You said the CIO hasn't worked-maybe try water in the bottle....or when you go in, instead of a bottle just try rocking him -maybe after a few nights he'll adjust to just that and you can phase that out too.
My daughter is very different then my son in this respect so in some ways I just think each child is unique and maybe he just needs more time to let go of it. Which is hard on the non sleeping momma!
I will admit-no emails please!-now that our daughter is older we give her the bottle in bed and she goes back to sleep.