This would definitely be a tough proposition for myself, whether with my in-laws or my own parents. I agree with the second poster in that in a case like this it really does depend on the relationship you have with your in-laws. Personally for myself, if I were in the same situation, I might end up reluctantly doing it if it were my in-laws? If it were my own parents, I'd only do it out of desperation though - they absolutely drive me crazy many times. Then again, if each party can learn to keep their own space, it might be OK. Ultimately, I think you'd probably get used to it. It seems like the benefits outweigh the cons here. But you really would need to establish and set some boundaries and expectations - if you can do that, reasonably, up front, then you'll probably be fine. The two big red flags are:
"- I don't feel like I could change anything to the house without offending my MIL
- If we ever wanted to move I think they would be offended"
If boundaries/expectations cannot be set around those things, then I'd say you may want to reconsider all this. Based on the phrasing though ("I don't think" and "I don't feel"), they sound like assumptions so it might be a good idea to bring those to the table with your in-laws and straight up ask them "for permission" for those things ahead of time.