Hey Dan, The RRS is a lot older than the D4 so the terrain response is much better. Not sure if the RRS has an e-diff or not(don't think it does) but the D4 does so that helps in some situations. Longer wheel base of the D4 also helps with larger steps too but ramp over angle on the RRS will be better.
Jamie's RRS has been through the wars. He has really pushed it hard so not everything is ship shape - he has had some traction control issues which stuffs him up some times.

