So, been struggling a bit to get a chance to actually work on the car, FINALLY had a combo today of time and not-freezing-temperatures in the garage.
Good news is that it appears I've managed to get the carbide burr out of the hole. Looks like the automatic center punch idea was the trick (Thanks, I believe it was Bruce). A few solid chunks came out and once I saw that I was actually making dimples in the bottom of the hole I knew something had changed. Cleaned it out and used a scribe to feel things out and it's got the profile that burr would have left, and no signs of the burr itself. But it seems there's still some of the old ez-out still in there, so I can't get at it with a drill bit JUST yet.
I've got another couple of those burr's on the way, since I know they can get through the ez-out. I just need to be more careful and not lay into it with so much pressure. It's a burr not a drill. I'm sooooooo close to being able to have a bigger ez-out grab into the bolt.