I replaced mine with motorcraft from Tasca. Almost the same price as the MSD's, but I think the MSD's sell for about $50 cheaper for a set of 6. Had been waiting for MSD's to come out forever and decided to stick with the stock ones on my 120k mile truck, as there wasn't any apparent advantage to the MSD ones. Nice to see that someone has tested the MSD ones and confirmed more voltage output, although I doubt this really translates to significant power gains.
If I could do it again, I would go with whatever is cheaper.