The affinity of 7a-Me-E2 for the Estrogen Receptor is 1% higher than E2.
If you assume a 1-to-1 relative aromatization rate, (e.g. that 100mg of Test and 100mg of Trest produce equivalent amounts of their aromatase metabolite) then the gyno risk is no different than running Testosterone at <whatever Trest dose>.
The idea that there is some "synergy" or potency-enhancing of Trest to standard E2 is false.
Because both E2 and 7a-Me-E2 bind to the Estrogen Receptor, they COMPETE for binding at target sites.
This is the same principle behind why you can't squeeze more gains out of taking more gear whose primary target is the AR -- once AR receptor saturation occurs, there literally is nowhere for the steroids to "dock" to exert their effects.
You have to look to compounds whose primary mechanism of action is not via the Androgen Receptor, like Anadrol/Winstrol/Anavar.
----
Honestly, I don't know where people on the internet come up with these absurd broscience ideas, and why others continue to parrot them.
They're so easy to debunk if you do basic bloodwork and scientific research.