Welcome to the board!
I looked at both and purchased the Powermatic. It came packaged with a free riser block kit, which included the longer blade. I have only resawn material that is about 8", but it did just fine with a sharp blade and good solid fence.
I don't have much experience with the Rikon. I purchased the Powermatic based on discussions with woodworkers and the guys at the tool shop, as well as taking a "test drive" with both machines.
If possible, go to a WoodCraft store and see if they've got one they can show you in their shop. You wouldn't buy a car without a test drive, would you?
Hack (a.k.a. Jeff)