well, since only one of mine was bottle-fed til a year (other 2 breastfed), and then he switched to sippy cups at around 13 months with no trouble, i don't have a lot of "practical experience" with this - but as a preschool teacher, i have seen the results of kids drinking anything other than water at night. the term is usually "baby bottle mouth" or something similar and it rots their teeth, even when diluted! they should have their teeth brushed when going to bed, and then have only water after that, unless they wake up to be fed in the middle of the night and even then, it's a good idea to brush again after that. i have seen 4 year olds with BRIDGES for front teeth or some with all their top teeth pulled way too early and they have to go years with no front teeth! but even though they are "only" baby teeth, cavities can deteriorate teeth and cause infection that can get into the bloodstream.
i am amazed at how many people (even someone like my sis-in-law who has a bachelor's degree in early childhood development!) keep their kids dependent on bottles even until the ages of 3 and 4, but i guess it all boils down to whatever is easiest sometimes. i know i let my sons have their paci's until they were ready to give them up (around age 2.5 for both), and even though it was alot less detrimental to their teeth/mouths than their thumbs would've been (and alot easier to get rid of!), it was still a struggle for me and my husband to go without sleep for a while, listening to them cry it out b/c they were so dependent on the pacifier to soothe them.
this is all alot easier to say 8 years later, but you know what they say about hindsight being 20/20! if i had to do it all over again, i never would've given them pacifiers and would have tried harder to teach them to self-soothe - i would have just gotten even less sleep, i guess!
please don't take this as overly-critical, as i know it probably sounds, but as one mom already mentioned, losing a little more sleep now will be easier on the pocketbook than paying for expensive dental work when they are still in preschool or early grades, and then braces when they are a few years older, too! some of it is hereditary and unavoidable, but we should all do what we can as parents to prevent any future health problems for our children. nip it in the bud NOW while he is still 2 - it gets harder with every year! most children at his age are very capable of hearing your reasoning and will understand the concept of getting to be a "big" boy or girl, but as with anything that anyone of any age is addicted to - it is easier until you feel the need, and then you just don't care! you will have to guide him past the separation of his comfort item in any way you feel will work best for HIM, not for you or his daddy or his daycare workers, if applicable. either wean him slowly or quit cold turkey, but do it now rather than waiting!
best of luck to you! :D