I've got 2 Cockers - Milo is 1/2 show x 1/2 working Cocker and Mocha is a show Cocker (although she's a rescue but was sold to her previous owner as a show Cocker).
TBH, I thought Milo was energetic and busy, until we brought Mocha home! They are both very active on walks, but Mocha is more active and charges around like a lunatic. She is definitely more of a hunter too, and is constantly on a scent when we're out and in and out of all sorts of cover. Milo tends to stay fairly close and almost "paces" himself.
At home though, Milo is much more alert and active and always looking for us to do things with him, while Mocha is generally crashed out on the sofa. To see her now (fast asleep next to me on the sofa), you'd never guess what a lunatic she is out on a walk.
I don't see a problem in keeping a show and working Cocker together. In my experience, a dog gets used to whatever level of exercise it has always been given, so can't see why a show Cocker couldn't do long walks with you and your worker. (Except when a very young puppy, of course. )