Kitchenaid stand mixer-ice cream maker attachment??
I have both the KA attachment and two ice cream makers, a Deni and a Cuisinart. The KA makes 2 quarts which is twice the capacity of the other units. It also has a much more powerful motor.
In both cases you have to freeze the bowl before churning your ice cream. The KA bowl which is larger, takes a longer time to freeze, around 24 hours IIRC. And it's harder to pour your mixture into the bowl which you have to do after it's attached and the motor is on - in my case I have a KA with a bowl lifter so there's not a lot of clearance. I got a funnel with a wide tip so I could pour the mix into the bowl without spillage. The Deni and Cuisinart have a hole in the center of the bowl cover which is convenient for pouring in the mix or other additions.
My main gripe with the KA attachment is that it doesn't fit my ancient KA well, the adapter doesn't attach to the motor head properly so when the ice cream begins to thicken, the whole attachment can slip off the head. I think this is a problem with my machine and not with more recent models.
Both make perfectly good ice cream. I think the KA dasher is a better design and churns air into the mix more effectively, but it's a small effect. You'll be happy with either.
For less $$ you can get an ice cream maker that isn't much larger to store, works on the same principle of the refrigerant sealed into the bowl and has a more effective dasher actually designed for ice cream making. Generally, my approach would be to make the appliance you already have do more but, in this case, I'd go with a $50 Krups or Cuisinart.