"Things one needs to note while using arimidex is that the benefits of estrogen become non-existent as well. First of all that means gains can be drastically reduced. They will be leaner and more qualitative, but they will nonetheless be seriously reduced. A second problem is that estrogen seems to have a positive effect on cholesterol levels. Since estrogen is reduced, the use of arimidex may have a profound impact on HDL to LDL ratio's in your cholesterol profile. In this aspect the use of Nolvadex is more user-friendly, because despite its anti-estrogenic effects in most tissues, it seems to exert positive estrogenic effects in the liver and promote a better cholesterol profile."

That is from bodybuilding.com. I was just wondering why would one use arimidex if they are using nolva throughout the cycle.