It'll cut MDF all day long, MDF is pretty soft. But you do lose that sharp definition when the cutter is actually sharp. I use double refined MDF for panels in my painted doors and I put a bevel on them so they fit in the slot nicely. It'll eat up the carbide after a while and you can see it in a pc of maple or other solid wood when you switch over. It'll actually leave a small hump, sometimes slightly burned because the carbide has been rounded over by the MDF.
When I was working for others I would make raised panels out of MDF. I would use the saw to score the MDF where the panel had it's shoulder. I noticed that the carbide would actually get chipped because the MDF was so hard on it. I got reprimanded by my boss for "wasting time" by doing the saw cut.
Then I went on vacation and he took over my position for the week. He apologized to me because he saw how the MDF damaged the carbide first hand. Told me to carry on.