My horse was very sensitive in the mouth when I got him and objected to pressure the myler full cheek comfort snaffle has worked for him.
My friends dwb has a big tongue and she now has him in a ported myler which works well.
I used a myler low port MB04 for my boy who has big tongue and small mouth. He went well in it but leaned against it so have now moved into the neue schules. He loves the team up and the tranz and I get the 16mm and it fits well and he doesn't lean heavy on my hands it lifts him nicely.