Name brand will have more R&D into the frame design, higher QC in production/post-production, and more control of assembly and distribution. As said before, also better customer service and warranty service at dealers. If you plan to buy a bike, and hold onto it a long time with some peace of mind, spend the extra few bucks.

If you don't plan to hold the bike very long, want to save the money or willing to take the risk in breakage - feel free to shop off brand. To each his/her own.