About right, except I'm not sure if 1.2 had prevented new stack formation (or depositing an accessory or similar). I myself love the new quick stack button as it makes depositing things like banners, herbs, blocks, etc extremely efficientOn a quick note, the way you describe the 3 modes relates to the following:
Unlocked - How quick stack works since 1.3
Locked - How quick stack worked up to 126.96.36.199
Hard locked - Not implemented yet, but surely useful ('deposit all' should also not work here, imo)
Since the new 1.3 update, quick stack has mostly been causing chaos for me. If you ask me, the new mechanic since 1.3 could be removed entirely, going back to the old quick stack system. A menu option to switch between them would also be a useful feature. Anyways, full support.