Your girlfriend is already morbidly obese, she has PCOS, so her weight will continue to balloon... I really don't think that this is a healthy person. (As everyone else said, she may not have health issues other than the PCOS yet, but she likely will.) I'm younger (23) and I don't have any health issues yet, but I'm almost 267 pounds and 5'7", believe me when I tell you it's a hard world out there for a large woman of any age.
I understand and acknowledge your fears for her, and I'm sure she is gorgeous at her current weight, but even if your girlfriend is getting the surgery to be "thin" I have a hard time realizing why you're begrudging her this. If a person is unhappy with themselves, they should try and change whatever it is that is making them unhappy. She's obviously not doing it for you, but for herself, so I think that in itself is a good sign that she will not regret doing it. Since it's virtually impossible for her to lose the weight the "old fashioned way," this is a great tool to aid her in her lifestyle change.
It's my belief that you should be supportive of her, and that you are being a little bit overprotective (not that it's not fantastic that you're wanting to research it more), just try not to focus on the bad you hear about the band, because the people with horrible experiences are few and far between. And 90% of the time it's user error, nothing to do with the band itself. Every surgery has its risks.
I wish you and your girlfriend good luck with whatever she decides! :rolleyes2: