I love Rosy Boas and they will always have a place for me, but just not with me anymore. That said, they are prone to RI's and are much more unforgiving of husbandry errors than most other littler snakes. Up here in NY, I haven't heard of many people having good luck with them. They are awesom pets with a very unique and loving temperament. Great for kids and stay small enough to house easily. Just be very careful of the temps and humidity levels with them, very picky. I could only give them a water dish two days a week. They are also very prone to stomach issues. I had one die from bacteria build up in the intestinal tract before. She was older and would always go off feed during the winter months, this year she did not make it out. RIP
Great snakes, especially for drier climates, and quite the variety to choose from, both locality and morph-wise. From the ones I've worked with, they have an amazing feeding response, especially tactilely. A fellow local herper has quite a large collection of rosies (read many hundred) and every single one of them will try to eat you if it smells like mice in the room. I would doubt this would be a problem with regular handling though.
That being said, I would suggest a KSB over a rosie. They are less sensitive to husbandry problems. Either way, you can't really go wrong.