I had surgery eight years ago at age 55. No diabetes, though - just obesity. SUPER obesity. Also, borderline sleep apnea that I didn't know about until I did a sleep test for surgery. I lost 235 lbs and gained back about 20 lbs in year 3 post op (a 10-20 lb rebound weight gain after you hit your lowest weight is very common). Maintained ever since, but it's work. On the other hand, before I had surgery, the most I could lose was about 50-60 lbs, and every ounce of it would come back. Happened dozens of times. So yes - weight loss is sustainable after bariatric surgery as long as you monitor yourself.
I had strictures at two months out and four months out. Very easy fix. The PA at our bariatric clinic told me it was the most common complication, and that they happen to 5% of gastric bypass patients (and if they're going to happen, it'll be during the first three months post-surgery - they're very rare after that). I personally wouldn't call something that happens to 5% of people "common", but that does give you an idea of how common complications are. Basically - they're not very common.
about 30% of bypass patients have dumping syndrome. I've never had it and most of the people I know haven't had it, but some of us do. It's caused by eating too much sugar at one sitting (or for some, too much fat at one sitting seems to set it off). It's because food passes through to your small intestine much more quickly once you've had bypass, and your intestines go into overdrive trying to deal with the sugar (or...fat). It can be prevented by limiting the amount of sugar you eat at one sitting (which we should be doing regardless, even us non-dumpers).
good luck in your decision. Honestly, I should have done it years ago. My only regret is that I waited that long to have it done. My life has changed dramatically for the good. I'd go back and have the surgery done every year if I had to - it's been terrific!