This is my vision of the perfect stash;
Each toon owns the first 5 tabs all to themselves; they are character specific.
Switching over to the new window they introduced for the new tabs will have just one tab now, and that one is shared.
I'd love this because one tab isn't NEAR enough for one toon. Yes it can hold 4 sets, but there is not enough room at all for the supporting legendaries per set. Instead, having a whole 'page' per toon would be more than enough room, and if you want to switch items over just throw em in the shared tab.