Another good source i've used is Culver. I've had them make props for a varieze with good results. I also asked them about making an 8' + diameter propfor my R-680 and they were able to show me some large diameter props they had made up recently.
I'm a "lurker" on the TailwindYahoo Group.Several of those guyshave Cattos on their planes. From what I read it's smoother than the Sterbas they've been using and pulls the plane through the air faster. (of course that can be from the twist on the prop too, but they didn't say)