200.20x should be able to be pushed faster at similar presures. 208 ELDm has a little BC bump and will have a shorter "neck" terminally which may be more attractive on deer at least.
It really just depends how you define "chasing rainbows". I've watched a lot of animals get shot with a 300. From the cheapest crappiest junk to cutting edge good stuff. It really all works.
I think its worth at least trying the two you mentioned though.