bontai Joe,
The 520xi can easily plow up to 12" of dry/powder snow with no problems. That's what most of our lake effect snow is. I start to have problems when the snow becomes wet/heavy. You just have to take smaller amounts of snow with the blade. I've read a lot of your posts about snow plowing, so you know what I'm talking about.
I have a walk behind Ariens 9/26 snow thrower if the snow gets to deep and out of hand. It's new, and I haven't use it yet. I just rather use the 520xi and the front blade if possible. We're suppose to receive more snow throughout this week. Possibly another 12" within the next two days.