It should be noted that the Monster Ball map is no longer hard coded with with Halloween zeds. That map now spawns whichever seasonal zed is currently active, if any.
I, for one, would love to see options to pick and choose any seasonal variety of zed in the options menu and switch them up as I please. Pukey the Clown doesn't do anything for me but some of the others are amazing compared to the vanilla variety. Some seasons are busier for me than others so I can't always enjoy the variety as much as I'd like.