I would test ride a lot before purchasing any of those bikes. Also test ride those other companies bikes you mentioned. I test rode a diamondback hardtail just for fun and was dissapointed - even though it was a cheaper model (400 - 500). It just didn't seem to have the smoothness of the low end models from specialized, trek, kona, etc.

DO test ride though, its really the only way to know for sure if you are going to be happy with it.