i've seen the new x5-R in person. And really there isnt much differences at all, and your older prosec or regular versions could be easily upgraded to an R-version over time, and with spare parts left over for more tuning options.

Really the only differences are

Shock Tower (the look very narrow like the Losi tower)
Shocks (very long)
Front Upper arm (more clearance for the ackerman)
Front Lower arm
Rear Lower arm and
Servo Saver.

edit

also longer rear wing mount.