If you are estrogen sensitive I would agree that avoiding gyno surgery should be seen as important. But the decreased gains things is still highly talked about and I really cannot say yes or no that you will lose gains from AI or make gains from NOT USING an AI. But if you take one look at Khemix , his physique speaks for itself. Doing what he does would probably be a good start for anyone...
1. Several studies have shown that Letro and Arimidex increase IGF-1. Not that those studies were done on females w/breast cancer
2. Dan Duchaine has said on a few occasions that allowing steroids to aromatase leads to increased serum IGF-1. So if one were taking 250mg Test E vs 1g Test E the sides would very greatly and the sensitivity of the user would play a big part in that
3. While using an AI, testosterone remains intact w/less SHBG (the effect of lower estrogen from the AI) so the active drug remains intact in the blood for a longer duration.
So from the items above you have to make a decision what is more important to you and you have to find out what your sensitivity to estrogen is.
Also if your taking a nandrolone ester , nandrolone is going to aromatase whether you use an AI or not... AI's have no effect on nandrolone aromatase