I agree with Madcow1. If you want maximum back stimulation then go conventional. If you want more back work than that, go conventional off of a platform.
For you powerlifters...don't convince yourself that your a sumo DL'r too soon. I've seen several lifters that were convinced they were sumo lifters go up 50 lbs+ by going conventional and sticking with it. I thought sumo was great because it's easier and more confortable at the bottom than conventional. Then I went back to the ball popping conventional and blew away the sumo max. I think you can grind out more wt. at the lockout conventional for the typical body type. Personally I think most people gravitate to sumo because it's more confortable, and I agree, but I want to lift more. So unless your very compact, stick with conv.
For reference, my sumo is 605+, but conv. is 650+. I always train both since they are complementary.