Most people buying D9 based memory have had the sense to go to the source and buy Ballistix, so it's expected that the majority of problems have been Crucial related. But the other brands using D9 have been reported as failing too.
This was my line of thought too. Seems like more people use crucial than other brands, so we're going to hear about more RMA's. But the percentage of failed dimm's is probably the same, if not less, than that of other memory manufacturers.