I guess whether the Pro-X is worth it or not depends on you. I bought mine, because the stock pedal was driving me insane by randomly missing pedal presses and randomly splashing. I would try to chick chick chick chick 1 2 3 4 a beat on the thing, and I would get chick silence chick splash, making the exact same foot motion four times in a row. It was frustrating.
The Pro-X is also frustrating. I have screwed around with this thing for a small eternity, and the only way I find it to be usable is when setting the threshold EXTREMELY high, so there is no dynamic range, and even then it is a two-position hi-hat. Open works, closed works, and everything in the continuum in between is going to make a random noise that could be one of silence, splash, or some degree of half closed pedal.
It really doesn't work worth a rat's ass to be honest, but the pedal didn't work worth a rat's ass either. The hi-hat on the DM10 is FRUSTRATING in the EXTREME. Considering I have over $2,000 invested in this rig, it's pretty bitterly disappointing that it's such total and complete garbage.
On the other hand, I get along fine treating it as an open/closed hi-hat, and I have a hell of a lot of fun bashing my drums. I have no desire to go back to the pedal thing, just because this Pro-X feels more natural. Even if it does sound like I'm hitting an empty bucket every time I hit the noisy thing.
Meh. You can't have everything. If I wanted something that would work well, I would have bought the Roland TD30-KV. You have to step all the way up to the $8,000 flagship to get as many drums as what the DM10X-Mesh kit comes with out of the box, and the Roland stuff isn't expandable.
I'm hoping that new thing coming out later this year will be the upgrade I seek to find total happiness. I'm hoping to buy the brain and the hi-hat, and don't see any point in upgrading the rest of my stuff here. My drums have frustrating limitations, but they're still enormously fun to play, and I love my Alesis goodies, even if the hi-hat is total dog turd.