Has anyone experienced problems where a promotion put you in a position of authority over friends within your unit?

Just remember, true friends wouldn't ask you to compromise your integrity.

Of course. Actually, most of the soldiers under my responsibility immediately after my promotion to SGT were guys that I was very close to.

Yes, that is why it is important to not over socialize with friends when you are going for your dreams. It can be awkward to lead friends who may know your dark secrets and have the potential to exploit them. Remember the crabs in the basket, they always try to grab the one trying to climb out! I might get out of the basket, if necessary (ie. ask for a transfer, if it got too awkward). Best of luck!