Dan, there aren't any local dealers that sell grex nailers (there website search engine was down, so I'm not that certain). I would like to hold them prior to purchase, but I've found the FOG to be a pretty reliable resource for feedback.
I have an old senco that hisses each time I fire it, and sometimes doesn't even fire a pin. I don't think I need anything longer than 1 3/16 so the 635 might be too much gun.
Jon