diamond backs arn't all that great from the start. the frames arn't very good. the response sport doesnt have a very good fork, brakes and i think its heavy and im not sure of the price. i cant find the xe but i found comp and its more pricy with not much better components but i still dont know how much it costs. the specialized hardrock sport is a really nice bike for 500 and the specialized rockhopper is very nice for 640. id look into those 2.