They still use it on all of their launched coasters. Powder Keg, plus the three big S&S launched coasters in the Happy Valley parks, plus one more being built in China for next year. The big ones are still the fastest-accelerating coasters in the world right now.
Being one of those "normal people," this is definitely unscientific, but Powder Keg's launch feels more sudden to me. The LSMs feel like the rate of acceleration increases as the launch progresses, whereas Powder Keg feels like the rate of acceleration is fastest right at the beginning, and then the acceleration slows after that. No idea if that's actually true, but hopefully that makes some sense to you. I'd love for some more coasters to be designed with compressed air launches. It's a really fun experience.