Two main problems with aromasin in PCT -
1. Its a steroid. that means its either going to directly (albeit only partly) inhibit the hypothalmus from releasing LH & FSH, or its going to act as an anti-androgen which can cause other problems.
2. Its going to reduce estrogen to the point where it will negatively effect blood lipids, libido and general health.
I never recommend steroid AI's during PCT unless you are running a heavy dose of HCG, which you should have ran during the cycle anyway.
-Eric