Has anyone ever tried this? In the Thieves Guild, would the Guild really require you go into your own tower and steal your own staff?

you just borrow it, it's ok i'm sure.

This kind of conflict with the player becoming the head of every guild, or for that matter even joining every guild, was something they didn′t really see through. Or perhaps they did....?

Well, the guards dont know your in the thieves guild. Your just putting it somewhere and blaming someone else for it.

In the original game, Bethesda didn't realize that that particular Thieves Guild quest would potentially require you to steal from yourself. Although nothing major happens, it does violate the continuity of said quest.

The UOP fixes this by giving specific journal entries explaining what is going on if you happen to be Arch-Mage when performing the quest.

The staff the Thieves Guild wants is Hrormir's Icestaff, not the Arch-mage's own staff, and it appears in the chambers mysteriously when the quest is given. It's not clear why it's there, or who really owns it - presumably the Mages Guild collectively as it gets returned to them..