I have a Gabriel, and we don't shorten it to Gabe, although some of the teaching assistants/dinner ladies at school have done.
It really bugs me that so many people insist on calling him 'Gabrielle', though. I always tell them 'it's Gabriel, like the angel', but they still do it, even people who should know better (like his new teacher who in 6 weeks has never spelt it the same way twice...)
I still think it's a lovely name though. I loved Raphael as well, but thought it might be hard to carry off, so ended up with more 'chummy' names for my other 2 boys.