Personally I would like to see both focal planes used.
Imagine, if you will, German #4 posts in the second plane,
Then in the first plane, hashed mil with open center or open center and a .1 mil dot
Wouldn't that be somethin'?
Would be neat, but if you wanted to be able to dial it and have them move together two erector assemblies adjusting simultaneously would be quite the challenge mechanically I'm sure.