I've got to say, I'm impressed by the Heavyweight Snare as well. It's amazing on my Pork Pie Big Black brass snare. I generally use a G2 or an ST on that one, but I think I may get another Heavyweight for it, once the current one wears out. It definitely doesn't feel as stiff as I thought it would, like the EC Reverse Dot snare batter head.
However, I'm not as much a fan of the Heavyweight EMAD. I'm having the same problem I had on my previous 3 EMAD-style heads (GMAD, EMAD2, EMAD Onyx) with the thinner of the two foam muffling rings falling out of the plastic portion while playing a set.
Let's not pass judgement before we play the head... ;-)
Both the Heavyweight snare batter and the EMAD Heavyweight are incredibly dynamic (far more than you would expect out of heads that thick) and are actually quite versatile. You may find that they're not the ones for you, but there are many people who have been looking for the ultimate durability without the sacrifice of dynamics.
Kenny Aronoff is digging it, Anton Fig is digging it, Matt Halpern is digging it.
With regards to the EMAD Heavyweight, the sound is incredible and the tone (even will feathering the kick) is full-bodied. From the moment I mounted the first prototype on a kick drum, this head became my favorite EMAD.
The heavier the head and the tighter the more energy is passed up the sticks to your hands. I have a slight case of arthritis in my hands and normally play with the snare batter a little loser than I want to help absorb some energy. I don't play out so the only personaware of the sound change is me. I like tight heads but have had to loosen them a bit as I got older.