I have had the chance to see this new BCA Mountain vest and it is great. I was skeptical and thought it would feel heavy, or constrictive but it doesn't! You almost can not feel the weight of the back with the design and how the weight is distributed.
The storage will be small for some at 12 liters. I currently have a Flat 22 and its more than I need so the 12 will be perfect. The production models should also have an external shovel holder which will gain back some of that space which is lost.
Next year I will be wearing one for sure. I expect they will sell a lot!