I own both. The Roll Design are Bitchin'! I also just had Rodger at Fireball build me their Long Travel arms as well, but they are done in light weight chromoly. No good for trails, but the craftsmanship is Top Notch as well. Have a normal set made And I bet you would be just as happy as running the Roll stuff. The roll arms are about $1200 and the Fireball stuff is about $800+ after powder coating. So the biggest difference is price. Aside from that, Fire Ball is now using an updated ball joint set up that is pretty killer.
As far as rear suspension components, I'd say a nice swing arm with a round house style carrier is needed. Also a RPM Dominator axle is top of the line.
Shocks... I'm more in to the Axis or Fox Floats. Elka seems to have a dwindling track record when it comes time to send them anything.