This is the one we have:
Amazon.com: Back to Basics IC10893 1-1/2-Quart Ice-Cream Maker: Kitchen & Dining
I just noticed that there are some bad reviews there, but as long as you make sure your freezer is 0 degrees F, and you leave the base in for 24 hours, it should work perfectly.
I mix up everything but the chocolate, turn on the machine, and pour it in. After about 7 minutes, I add the shaved chocolate (put it in at the beginning, and apparently it won't be well-distributed).
After about 10 minutes total, you hear the machine auto-reverse, meaning that the it can no longer turn the paddle, and the ice cream is done.
It's amazingly good right then. If you put it in the freezer, it gets a lot harder than ice cream that you buy at the store. The trick with leftovers is to freeze small bits (e.g. 1/4 cup), and defrost them a bit when you want to eat them.
Also, some of the ice cream will be frozen to the sides of the maker. Put it in the fridge overnight, and you can add the ice cream to your waffle in the morning.
I've never made it with sugar. It turns out fine with the splenda, however. I think there's some kind of splenda-adaptation that occurs, so that if you haven't used splenda much, you might notice it. It would probably be better with a combination of splenda and erythritol, but I like it fine the way it is, and don't want to risk experimenting.