Mav makes good points.
A50, I think one thing to consider is how sensitive you are to gyno. If this is a problem for you, then I think using the Nolvadex is a really good idea. Nolvadex, as you probably know, belongs to a class of drugs called Selective Estrogen Receptor Modulators (SERM). And while it is a competitive inhibitor at the estrogen receptor, rather than an enzyme inhibitor like Arimidex, it is specific for breast tissue.
These drugs were developed for breast cancer patients who have estrogen-sensitive tumors, and it's not uncommon to have these patients use both.