I don't understand why AB has the issues he does with dust as I don't, but again having it precut will solve that.
Some folks have sensitive respiratory systems. Sometimes the MDF, and even plywood bothers me, i'm pretty sure it's the resins and not the wood itself, a big fan and good ventilation makes it pretty much a non issue.

Now certain weeds, and the weed eater or bush hog are another story and can leave me pretty distressed until i get to clear air, not a good feeling at all. So, i can appreciate and understand wanting to just avoid the MDF altogether for those who are really sensitive to it.