Do the math, though. For me, N was about $50 less per month, or $600 per year, than G. That's thirty $20 co-pays. There's a $50 copay for ER visits unless admitted to hospital, also, but not urgent care. The price will vary with your age and location.
And the $20 applies to "office visits" but not to most procedures. So when you visit the dermatologist and she freezes stuff on your body, it does apply. But if you have to come back for more extensive work, it usually doesn't. Medicare is complicated to the point of mystery.
I have never seen an "excess charge" which is something people worry about with Plan N. About seven states prohibit them anyway.