it's actually not a QOL change at all. In fact it diminishes it. I already had this discussion with another person on Dfans post Blizzcon.
What the armory does in terms of coding language is point an array towards your inventory. Its like using vlookup in excel. It looks up the info in your stash and uses that info for the armory.
So yes, you can have multiple builds per character slots. However, it WILL NOT free up any inventory in your stash. This is what people actually wanted, a way to free up stash space. Because what eats it up the most is multiple variations of the same set item due to RNG.
I think you're looking at it from a 'wrong' point of view.
It is a QoL-change in the sense that it frees up the need to make several characters, just to make build-swapping easier. It pretty much makes any kind of gear-swapping easy.
It changes nothing in regards to how you store your loot - it's not supposed to do anything in that regard - simply just make it easier to manage builds.
You are still looking at it wrong.90% - the majority of players don't even uses there alt for a different build. Since D3 Vanilla they've always used this formula = 1 main per class + a crap ton of mules. What are Mules? a bunch of Level70 characters that never get used for gameplay. Only used as extrensions of stash space. Don't believe me. Go ahead, run pole and go into D3 and ask people.
I guarantee you this will change nothing. People will be very disappointed with what they are receiving this coming 2nd or 3rd quarter.
You really shouldn't use percents in a already failed arguement. I have 1 of each character and 4 crusaders. I have a hammerdin', a lon bomb, a Roland's I hope that gets fixed, and an invoker. This excludes season characters. So yes armory would allow me to delete 3 crusaders and use those 3 as mules for odd ball gear I don't use thus freeing stash space.