Unfortunately I haven't been on the Avalanche yet to judge it. All Virus boards are handmade in Germany, and every review I've read has judged them VERY highly.
The nice thing is if your size is a good match for a certain length board, but you like something stiffer/softer, he can make that too.
They have a traditional camber profile with a lifted nose for powder float, so they are very similar to the Custom X with the exception of the nose.
Right now I'm riding the angry brother of the Custom X (Burton T7) and I think the Avalanche will be a step up, otherwise I wouldn't be buying one!
If it's something you're interested in, have a look at that thread and Virus' website and get back to me. I want to put the order in soon as they'll take a few weeks to make the boards and snowboarding season is upon us in Calgary.