Sustain Alpha is great at raising testosterone, and increasing libido...which also raises testosterone
Yes, the 7,8 benzoflavone in Sustain Alpha is a very efficient/potent AI, particularly effective when used transdermally. So, yes, Sustain Alpha is great for lowering estrogen and boosting testosterone. but, this doesn't mean it will free testosterone. I've seen conflicting studies on the impacts of resveratrol on SHBG.
There are many methods for lowering SHBG, but would be interested to know if you have bloodwork.
To lower SHBG you could try something simple like supplementing boron. I'm not necessarily a huge fan of stinging nettle, as it will likely lower DHT...and that may not be what you want. But, stinging nettle can lower SHBG and increase free testosterone.