Although the X10 and XRS look the same, they are completely different. The X10 is a better buggy using alloy steering braces and front shock linkages (as opposed to plastic on the XRS) amongst other things. I belive the X10 chassis is also lighter than the XRS?
The XRS was about £220 and the X10 around £399ish i think??.
Both my XRS and X10, although fun to drive and very quick, seemed fragile and suffered from a number of reliability issues on a regular basis. (some of the fragility was my fault due to crashes)
Now, the new X11, thats the car to have of the pred range. Its a much better design than the others and it's alot stronger.
One of the guys i race with has the new X11 and it doesn't have the same reliability issues that mine used to, it also seems to drive alot better and handle the bumps and jumps better.