I'm an intermediate rider who has been renting for the past 3 years and finally sprung to buy my own gear. I've always rented burton boots and have always been a size 10.
I wore these boots around the house for a day or so when I first got them. Naturally they were a bit tight at first but after a few hours they were actually pretty comfortable.
When I took them to the slopes, I started getting some gnarly pain on the ball of my foot and the back of my calf. This might actually be the fault of the bindings. When I loosened up the boots, however, it helped. Of course then my boots were pretty damn loose. I know a lot of people hate that, but it works for me just fine. As long as they aren't in any danger of coming off :)
The lacing system is really simple. I still haven't decided if I like it more or less than the traditional lacing. It's definitely faster... but I'm not sure if it requires constant attention yet.