There's nothing wrong with the losi RTR's. If i were you i'd get the buggy. Its a tad cheaper and can be found brand new for around $500. You can find deals on used ones here for even less with very little use.
If you want to upgrade the servos, i'd go with savox, they are dirt cheap and seemingly very reliable. You can pick up one for throttle and steering for about $120-130 for both.
The RTR's are competitive, the engines are just fine for starting out and can get you on the podium should you decide to start racing. Everything else on the vehicle is optional and can be upgraded in pieces for cheap if you utilize ebay properly and buy parts in groups to save on shipping.
Overall i'd have no problem buying the RTR and racing it against anything else on the market including the race roller version of the 8ight. I have a race roller truggy and buggy and imo its more about the driver skill and not so much on the vehicle itself. Of course it needs to be setup properly, but thats easy to do, as there are several guides and setup sheets available directly from Losi's website.