Hold out for the new X 4.6 RTR if you DO decide to go the RTR route. has aluminum diff cups and a bigger engine and better brakes out of the box.

If, however, you're not too worried about the price of the initial plunge and honestly want what's better, get the X SS, drop some coin on a decent radio ($150 should do it in most cases), a decent charger, steering servo, etc etc and so forth. You'll be 100x happier in the long run, because you won't be upgrading the RTR to parts that you would've gotten in the first place with the X SS (like the HD dogbones, dual disk brakes and such)