Who is recommending long-term? I'd ask them why and what she might gain/lose (worst case scenario)? I'd assume if short term crisis/acute hospitalizations haven't helped her (having had 6) then it might be time for a longer, evaluation/med check, etc. trial?

You too are influenced by your daughter's illness and could use the longer time to recoup some of your own energy and make plans for the true long-term, see what might be next if things go well/ill.

I don't know that you can predict how your daughter will/will not do or whether it will help or not further than researching the hospital and staff and their "success" rate, etc. as one would before any important medical operation? I'd learn all you could from three sources, those who think it might be a good idea and those like the one whom you have already spoken with who don't like long-term care but also speak with people who know your daughter!