Fantastic post, mate.
Some of the newer gen MWS’s have different float valves that lower the FPS. The gen 1’s were breaking the 1j limit in Japan under certain conditions so they changed it. With gas guns you’ll always get a larger joule increase than FPS increase though because it’s a self adjusting volume system depending on BB weight
I was getting a 60ish FPS increase with a 410mm. It could be the amount of hop applied, or perhaps it isn’t creating a good seal with the bucking. If it’s consistent it shouldn’t be that though.