Well according to Dr Mark Gordon who is probably the leading TRT doc in the US, AI's do more harm than good unless you have excessively high E that cannot be controlled by other methods. He believes that the AIs get into the brain and prevent conversion of T to E there and that somehow interferes with growth hormone secretion. Dr Gordon has over 1200 patients on TRT and has treated patients that Dr Crisler was unable to help. Even Dr Crisler has stated that he does not like to put guys on arimidex unless absolutely necessary when they have symptoms of high E2 that can't be solved by just decreasing testosterone dose.
Normally small frequent doses of test do not require an AI! I have seen many lab results that confirm this. The guys who are doing ED and EOD shots cannot increase their E2, or DHT for that matter. Like him or loathe him, Dr Scally on Meso-rx has also stated several times that an AI is not normally needed in TRT.