I'm not familiar with Myodex, but I've tried "herbal" E blockers which I got off the net from iHerb.com. I got DIM, or diindolylmethane to give it its proper name, and I did have good results with it. I had a look around some endo journals and it seems there is actual evidence that the stuff helps reduce E. Anyways, it did make me feel a lot better. I found I had a lot more energy, felt better in myself and more comfortable in my skin, and the estrogen dominance symptoms I'd been having went away.
I took the DIM when I came off E based birth control, which was doing horrible things to my body. Turns out E and my body don't play nicely together (whoever would've guessed?). After a few months I found I didn't really need the DIM anymore and stopped taking it.
From memory, the stuff was quite cheap through
iHerb.com, so I would say get a bottle and see how it goes. But please don't take more than 200mg/day because the endo journals suggest that could be bad for your liver.