I was taking anavar and testosterone and I *still* lost muscle. And T3 drastically lowered my thyroid output according to bloodtests I had done several weeks afterward - this happened to several friends of mine as well.(not into hypothyroid range, but much lower.)...all of this with only 25mcg of cytomel.
This may not happen to you of course, but I would not recommend T3 to anyone. The risks are too great, IMO.