I inferred it from statements made during/after the spring update and the iXtreme rollout as well as confirmation in #fw and statements on this forum
MS is not saving ban-related info to HDD (at least not yet), but they save it to flash.
If this is inaccurate, I would certainly like to be corrected. If the answer is unknown, then I'd be ok with that too. I am just curious, if it does in fact store the boot logs, what information is known about them.