Percentages, most likely, even if you take into account the fact that the Talons should be stronger. In truth, only a small number of these hubs have failed, relative to the number of bike in production. An even smaller number of '06's have Talons on them. Assuming the same percentage of Talon
equipped bikes would be subject to chain tension errors, that number would be so small as to be statistically insignificant.
If the chain is a little too tight, the swing arm can still pass over center even though the chain causes it to bind as it does so. The total assembly flexes enough to allow it. If it's a little tighter, things have to flex more, and the stress applied to the associated components are magnified. It's unlikely that the first compression of the rear suspension would break anything, but certainly conceivable that the cumulative effect of 20 hours of such a thing could. And, maybe (fairly obviously) the hub is the weak link in this "chain", and maybe the ringless centers of Ironman sprockets contribute.
I'm not trying to point fingers, blame anyone, or absolve Yamaha
of the responsibility that may be rightly theirs. I'm just pointing out that chain tension is a very likely suspect as an underlying cause, and it's one that can be easily followed up on to avoid it contributing to such a failure.