No, I don't own a GS Air M or MS. I bought an Ego One tank to go with my Ego One battery. I was responding to this post
I have tried my GS Air on the Ego One battery and it's a much cooler vape. It vapes fine, much like running it on an istick at about 9-10 watts. I believe that the M and MS are very similar to the first GS Air since they use the same coils. The M and MS are 19mm and the first GS Air is 18mm so it doesn't look as good on the Ego One battery.
The M or MS should fit perfectly.