For me, no; pannier rack for MTB is $$$$! Until I can work out the details of my own design, I can't even try panniers. But my experience to date with carrying cargo on the bike instead of on ME is: not in favor of it. I can manage the weight better when I can control it with my body movements, as opposed to tweaking the bike to compensate.

If the day comes that I AM able to try them, I'll likely get something mid-priced; I have a distrust of Nashbar.....