I have only ever used my crackdown original because I play it on live though..
Anyway could it have been something added to newer games and those who have not played these certain games are the ones not banned?
The only person I knew who was not banned had only played GOW as a backup. The others had been playing C&C3 (including me). When the unbanned person played C&C3 (today) he was banned pretty much immediately.
Anyway, wouldn't the most logical thing to do be to get all the people not currently banned to post specific information as at the minute we are getting things left out from most people.
Specifics such as drive make and version, how it was modded (eg resistor, bad flash), when purchased, updates used, when was it flashed, which firmware flashed, any other flashes, whether they were refurbs, stealth media etc.
That way we'd clearly see any trends easier.
I'm not saying there is anything in it or any way round getting banned.. as all those not currently banned could be banned any second.