I have built 10+ computers over the last year with them, ranging from the 300's to 350's and never even so much have had a power issue with them...They seem to hold the rails quite nicely, even on the picky ECS K7S5a mobos...
Until I see otherwise or get a batch od duds I don't think I will be looking for a replacement part.
Yeah you could find cheaper, but for piece of mind when it come tothe dubious task of identifying power issues, it is worth it....