I was asked on Google+ why play ATS instead of ASL. My answer, though a bit of a waffle.
The ATS Armor rules are slightly easier. Rules are "only" 74 pages (2 column). Biggest reason, impulse turns instead of the more detailed sequence of play. New initiative rolls during the 3 phases of a turn. Plays a little faster.
There are a couple of ATS players locally which is nice. But there's also quite a set of ASL players as well.
The ASL rules seem more stable (on v2 with errata for sure) while ATS is on 4.4 and has undergone big changes to various systems throughout the years.
Some thoughts on the issue. It's a tough market for him. There's a complicated tactical game out there (ASL) and it's the go to game for the reasons I mention below. If someone wants an easier game there are better (ie easier, more accessible, etc.) to choose from that are also less expensive and easier to get. So why would one choose ATS?
I say all that as I'm considering getting some more ASL Kit as well.
ASL is more popular and more players can be found around the world.
ASL is better supported by the fan base. ATS is slightly more expensive (I've not done math here, just eyeballing it.)
Critical Hit can be tough to understand. But the couple of times I've emailed Ray(owner) and bought from his site, the experience has been fine. I know there are a lot of strong opinions of him floating around the web. He definitely has his detractors.
I'm riding the very expensive fence at the moment.