Hmmm, tough choise.
As already mentioned, local support are very important.
All the shaft car drivers I know, says that a shaft car is more direct in it's response to driver input, thus less forgiving. They say, that this requires an even better setup.
Both Yok SD and XRay are pretty stiff cars, which definately requires a good setup.
As far as I know, the new Evo2 comes with both C-hubs and pivot ball suspension, but you better check it out.
A couple of things I really like about XRay: They have good setup instructions. And access to adjustments are good too, diff, shock dampning, caster etc., can be adjusted in seconds. If the car is easy to adjust, it's easier to experiment, thus gaining setup experience.
Schumacher Mi5 - Sanwa MT-4 / RX-462 / KO Propo PDS-2123 - Nosram 5600 X-treme Saddle Pack - LRP SPX Zero/X12 17,5 - Nosram Stealth Touch Evolution - MAAS SPS 9250