First, I applaud any and all that buy avi bags and wear them.
Second, I don't care what the cost is to refill the canister. If I ever get caught in a slide again, that will be the least of my concerns (or expenses).
Finally, get the one that fits you best. A 30 litre bag on a short guy isn't a good idea, nor is a small pack like a ABS Freeride on a really big guy.
If you buy a used one, make sure to test it before you head out on the mountain counting on it. If it's an ABS model, that test will cost you $175. But in my mind that's still worth it.
My fav is the ABS Escape 15. Shovel #1 is inside my pack. Shovel #2 is on my sled so that I don't have to take the pack off my back when digging out, leaving the pack useless because it's sitting on the snow while I dig instead on my back where it belongs.
Just for clarification.
I recommend those with a BCA and Snowpulse using compassed gas to go to an authorized dealer. Filling these bottles is a bit different than filling a paintball gun and personally since this is a safety device I recommend doing it at a shop that is trained to specifically do this. It should cost you 5-15.00 to have it refilled and it should take 20-25 minutes. The bottle has to either be frozen down to minus 20 as when it is filled it heats up, or filled then allowed to cool and topped off.
ABS refill is done at the factory in Langley, BC. It cost $30.00-$40.00 and all you have to do is bring in an empty bottle and used handle and they will hand you a refilled bottle and new handle. Takes less time.
Yes to testing your bag and on a snowpulse and bca check the pressure every time you ride. With ABS you can weight the bottle, easy to do, I have never had one leak in 600 blow off's.
With ABS once you bags has been blown off 10 times, then it is time for a service as the carbon deposit from the pneumatic handle can block it, this is every 8-10 years at once a season.
I always encourage buyers to purchase and extra canister for snow pulse and bca or extra bottle and handle for abs as if you accidentally blow off the pack somewhere , then you are not going back to a shop, you are going riding, this way you can quickly recharge you bag, especially if you are at a backcountry lodge, this happens very little but can happen, likewise if you blow it off on a sunday and monday shops are closed but you want to ride. Having one between buddies is a cost effective way to do this.
All bags work but I encourage any purchaser to do their homework on fit, function, easy of use and repack etc. then make your choice...