I bought a 2008 CRG RR at the end of last year. Most of the kart was in good shape, bottom of frame had some off track scratching and the floor pan was pretty beat up, but the kart was in pretty good shape. Ask about last time motor (if not roller) was rebuilt and when the last time brakes were done and look at the rotors/pads to see if that looks to be about the same amount of time. Those gave me a good idea that the guy had done his maintenance on the kart, rotors looked good and he said he replaced it when the motor was done, 6 hours ago (according to MyChron) so the whole story fit with the condition of the kart.
Not sure about life being left in it, if it’s straight and not beat on, I’d expect to get some years of service out of it. I don’t expect to run at the front of the pack in S1 but I have seen guys in older karts than that best the newer CRG chassis. So I’d say it’s a great place to start in learning to drive a shifter.