D&D 5E Buffing the Champion Fighter

[S'mon]

I've seen people suggest allowing Remarkable Athlete to stack with Proficiency

Yes, this is my solution. Although adding half Prof to Init is a possibly-unintended quite big boost; still nothing like the Alert feat.

 

[Sadras]

I recently came across this - I think it might be a bit too god at level 18

Agree. I'd actually go little further and add that it's pretty good too.

 

[bid]

How many attacks per short rest does the champion need to make to break even?

At low level? Around 60 rolls, iirc. But you run out of health before.

The big joke is that the chunkiness of hp has more impact. That extra hit on a creature with 1 hp left will destroy whatever advantage you got from your archetype.