I agree that the Emperor X is very durable...it has to be - it's thick as hell!! LOL
I don't find it any louder necessarily than other heads (except that you can hit it harder cuz it's thick as hell) and I doubt very much that it would give you the sensitivity you require to play blast at 190 bpm and make it sound clean...again, cuz it's thick as hell!! I use one (coated) on my 14 x 6.5 Birdseye Maple Tama Artstar II snare so I speak from experience. It's not bad, but it's run it natural course and it needs to be replaced. I will be switching to a coated Emperor within the next few weeks. I wouldn't use an Emp. X again for any of my snares.
Keep in mind that any head that will make "weak hits sound louder" will also make "loud" hits sound louder so the difference will still be there. As you know, this is a technique issue, but I think you are speaking more about sensitivity when you say you're looking for a head that makes "weak hits sound loud" because a sensitive, more responsive head will help these weaker notes stand out more in the meantime, until you can play them evenly on your own. Is that right?
From your description of what and how you play, I think you should try something single-ply like an Ambassador or Powerstroke 3 (coated of course). Both are 1-ply, 10 mil heads. They WILL give you more volume/crack, and more importantly, all the sensitivity you need to boot. Also, experiment with moongels or O-rings (more so for the Ambassador, the P3 has a built-in dampening ring) cuz they can dramatically change the snare's sound (sometimes for the better, but not always). If you are concerned about single-ply's not being meaty enough in sound or durable enough, then try a coated Emperor (and again experiment with the gels and rings). The Emp is 2-ply, 7 mil each ply. I'm guessing you want more of a focused sound with less overtones since you play metal so you will probably like what an O-ring will do to your snare's sound. Incidentally, I prefer Yamaha O-rings because they are narrower and thinner than others giving them the ability to get rid of the unwanted overtones without killing the actual sound of the drum.. They're the best in my opinion. Also, using good snare wires is very important and will not only help you for this issue, but improve the overall sound of your snare. Look into upgrading your wires if you don't already have good ones. BTW, PureSound makes great wires.
I'm a Remo guy so I can't speak from experience on Evans heads, but lots of drummers use the Genera/Genera Dry/Genera HD/Genera HD Dry heads and they seem to really like them a lot so I'm sure there's some great options there as well.
I'm not a metal drummer nor am I a hard-hitter by nature, but my band's music is mostly heavy alternative so I do hit hard often enough. In nearly 3 years I have yet to put even so much as a dent or dimple in any of my heads. My technique is decent in terms of how I strike a drum, but it's certainly not anything to marvel at. A friend of mine was in a metal band for years and he used coated Ambs on his snare without any issues so you should be fine with a thinner head. Basically what I'm saying is don't worry about putting your stick through the head. If you somehow manage to pull that off, head selection is far from your biggest dilemma!
All the best,
Mike