I've only had one, and not by choice, that ended up in a tank too small with not nearly enough/large enough fish to clean, and died after about 6months. I really do think it would still be alive if it had been in a larger tank with more/bigger fish to clean/feed from.
I won't own another one for the simple fact that I think they are rather ugly fish.
Not because I don't think I could keep it alive "long term".