I've used both before.
High-dosing ATD kills my libido and gives me sore joints. Most strictly ATD products (inhibit-e, nutra's ATD, etc.) contain 25mg/cap. So, recommended dosing is anywhere from 1 - 3 caps (but i've seen some labels even suggest 100-125mg - retarded).... But you can't play with the dosages too much. I feel 75mg is too high, but that only leaves you with 25mg or 50mg...
As fayd mentioned, Arom-x contains low dose ATD (5mg) a 6-oxo metabolite, and stinging nettle extract. It allows you to play with the dosages a lot more with a maximum recommended dose of 6caps/day. You're a lot less likely to experience the two major sides associated with ATD (libido and joint soreness). I've also heard it helps lower the odds of estrogen rebound after PCT...
With all that being said, I'm currently having great results from my PCT with Arom-X. Libido is actually increasing and I'm feeling great...