Stuart has hit the nail right on the head, it's a balance, buy the best you can afford, remember you'll never say you wish you'd bought a cheaper one..... The accuracy advantages of the LX200 largely disappear with autoguiding with something like guidedog. The LX90 performs quite nicely as an astrophotraphy mount. see
http://www.users.bigpond.com/lansma/art_autoguiding.htm for details and pics. The LX90 comes standard with the Autostar suite and connection cable so can be driven from the p.c. without any additional equipment. The LX200 has larger forks for better clearance. The OTA on the 8 inch LX90 is identical to that of the equivalent LX200. The 10 inch LX90 is advertised already on some US sites. One thing I didn't realise is that the 10 inch has a larger hole in the mirror and is more suited to 2 inch diagonals and larger EP's than the either of the 8 inches. The LX200 can also be fitted with the new wireless remote which would be nice. That said, I think the LX90 will challenge me for a while yet and maybe when I've exhausted it's capabilities I'll trade up.