the 2011 Response sport is the best over the base overdrive and the Topanga fs is crap! Not a reg DB Only a SA model, way cheap
The response sport has a better drivetrain, but if you want a 29er the overdrive is not bad, basically same wheels, shock, brakes, lower end sram x4 24 speed on it instead of the shimano 24spd drivetrain. really decide if you want 29er XC bike or 26" "all mountain bike" ;;to sum it up quickly...