It seems like there are other factors that they look at besides time. I was a Air Guard E-6 with a 13 year break in service and lost one paygrade going to the Army Guard. Meanwhile a former Marine E-5 who was out longer than me kept his paygrade when he came back in. And on another note, he did not have to go to the WTC.
It's going to depend on what MOS you do, your original MOS, your current rank, your previous branch, unit vacancies, etc. Your time in grade will definitely be reset but you would need to talk to a recruiter in that state.
Do some research...many folks said I would keep my rank if I re-joined even with my long break in service (not as long as the one posted earlier). The recruiter I spoke with said I would go to E-4 and would not be able to keep E-5. I'm still pressing it but you never know.