Yes, it is a sugar alcohol. I had not been using it until recently and my ice cream was also rock hard. I was softening it in the Microwave. It was not until I added the xylitol that it became scoopable. I haven't had any problems (stalling or otherwise) by adding it. However, this is a YMMV situation.

If you can get your hands on Erythritol, it is probably a better sugar alcohol. I can't get it in Canada.