The Mammut packs appear to me to be the best tailored towards backcountry riders. Designed so that you can carry your board in split or together mode. Being able to swap out the system is nice. In reality, I am not so sure how handy that will be. I can see it being useful for hut trips, but I am not sold that their large pack is appropriate enough for that sort of thing. On top of that, on hut trips, riding with a large pack just sucks. I know that I always bring a smaller "sidecountry" style pack with me for hut trip laps. Maybe that is the way to go, a smaller pack you can bring on those trips. I'll be rocking the 30 this year.
Airbags work, I have no doubt about that. If I had to choose between having a beacon or an airbag, I'd probably take my chances with the airbag. They have had a much better success rate with live recoveries than beacons have ever had. Not that I am going to do that, but it's worth noting.
A bit of advice on the avy course thing. Get at least a season or two under your belt before going for your level II, if you haven't already. Level II is great, but so many people take it right after their Level I. They have no boot to the ground experience. You need some of that. The Level I course taught you everything you need to know to travel safely in the backcountry. There is nothing new in the Level II that is going to make it easier. You will get some heightened awareness to problems that aren't discussed in the Level I. It might allow you to make the choice to ride something you wouldn't have, but it's just as likely to make you back off.