Actually a good way to test this would be to sign in with a guest account. Someone pointed out a while ago that when you do this, they become an exact copy of you. Your rank, your fridge gun, your EE and NAV table/card status, and your money in the bank. After you sign in they become independent. His idea was that you could take all of the money out of the guests bank and hand it to the main account, effectivly doubling your money.
My point is I have used a guest account to get the quick revive perk, and I noticed after one such attempt (where I had to do it twice because I lost it when I tested it the first time) that the guest had ranked down to a skull (it had started as a knife, same as me). Once you reboot your xbox (or possibly just sign out/in again) the guest is then created as a fresh copy so you could track how many downs it takes you to actually lose your rank. I probably had about 40-50 downs in that game on the guest account