You could be right. I noticed on the picture of the M that the airflow adjustment is different. It looks a little bit like the slider on the Kanger subtank.
exactly. They are now doing a sliding adjuster similar to every other tank that is adjustable. I'm not sure why they ever thought that the screw was a good idea in the first place. Hopefully the M and MS tanks are as good or better than the regular GS Air. I fear that they may discontinue the regular one at some point since having both a 2.0 and 2.5ml is pointless.