I don't have FD's but I have Proto's with their anti-slip design. After weighing it all out, for daily use on cars, I find that I use the Proto's much more than my non-ASD wrenches. That said, I have both because I'm often working on motorcycles that have fastners I don't want marred up, so I'm very glad I have both.
And just another word on Proto's ASD; you have to SERIOUSLY be laying into a bolt before they leave a mark, and that's another reason I've become a big fan.
All that said, if I were back to professionally wrenching in cars all day long, I think I'd have a set of WrightGrips in my too box. I think they're perhaps a smidge better than the Snappy, and markedly cheaper.