If your parents are enthusiastic about it, rather than agreeing out of some sense of obligation, then it seems like a great choice.
I do think that setting that boundary about them treating you like a child might be dicer than you made it sound. You have every right to want, expect, and even require that. But they also have every right to behave however they want in their own home. This could easily be a fundamental incompatibility that makes the arrangement crumble.
I lived overseas and was evacuated during a major catastrophe. I went to stay with my parents, who I adore and with whom I have a wonderful relationship. But when I was in the middle of reading a chapter in a book and mom knocked on the door and told me she was doing a load of whites and wanted my whites to add, it got annoying, fast. Even though it was kind and helpful and not at all expected for her to want to do my laundry. I didn't want to drop everything to pull the white socks out of my laundry basket Right Now. Even as I was grateful for the place to stay, and for her desire to "help" by doing my laundry, it was an annoyance, too. But it would have hurt her feelings deeply if I'd pushed back too hard. (I tried, "I'll just do them myself later" and that didn't work, either because she really wanted to "help" or because she saw it as an inefficiency to do 2 loads of whites instead of 1.) Since I knew it was a fairly short-term arrangement, I sucked it up. But I couldn't have done it long term.
DH is switching careers this fall and depending on the timing of things, we may stay with my parents for a couple months. They are beyond thrilled; they'd like for us to actively plan for it to happen, though to use it is sort of a back up plan. But we are already preparing ourselves for being parented (in our late 40s). It's not something I could do long term, unless I'd exhausted most other options. The savings wouldn't be worth it to me, much in the same ways that living with a roommate wouldn't be worth it to me.
