2005 Hardrock Sport Disc for $350 or 2006 Rockhopper for $520? I know the rockhopper has a lighter frame but what about all the components, how do they compare? Is the tradeoff of having disc brakes vs lighter frame worth it? I don't mind upgrading down the road as long as the bike lasts at least year in its current state. I will be riding trails and street in SoCal. Thanks for any suggestions.