how much does the size of an aircleaner really matter in the real world?

I currently run a 4" cleaner on my sporty and have been looking for a cleaner for my new incoming dyna.. Now all the cleaners I find I like which head down the more vintage cast aluminium style are all 4 or 4 1/2".. Or big standard sized ones (not a fan) There doesn't seem to be anything in between.

Is a 4" cleaner with a foam filter going to restrict too heavily on a standard road going bike with which I'm not chasing horsepower.. Or is it really going to be a bigger is better case?