Dbol was literally designed to be an oral testosterone solution. Toxicity at the original 5-10mg daily isn’t going to be a concern for those without pre-existing conditions. For a 4-8wk oral cycle, this is definitely safe. You could probably even do a standard 25mg tab split into 2 doses and still be fine for most folks.
Alex Kikel has experimented adding estradiol in something like 40 of his clients and himself, no AI used, everyone pushing a good amount of gear. ~15% of guys had to quit due to gyno concerns. Everyone had better HDL, joint comfort and crazy libido. Listen to the Beast Fitness Radio podcast where he discusses the results. Conclusion was high estrogen was better, but NOT high as possible - there was a threshold where nothing got better and sides increased.
You could literally take DHEA or Dermacrine and be better off for gains and recovery than using estradiol. Trest or Dbol would be better options for bigger gains. If you can source Dbol you can get test tho, so why not use what your body really wants?
MOST IMPORTANTLY the joint drying from epistane isn’t entirely related to low E2. It dries them out to a degree regardless. I had joint pain so intense even on a GRAM of 4andro daily that I had to quit Epistane.