Z-Ultrat Z-PCABS and Z-ABS are not printable (currently) on the M300. As far as I am aware, the limitation is in Z-Suite as the hardware M300 is nearly mechanically identical to the M200. There are obviously many cases you could print in those materials on the M300, and major drawbacks with having a broken ecosystem between the M200 and M300. However, Zortrax has said that they believe that enabling those materials would provide bad PR for them, as people will try to print geometries they obviously shouldn't in those materials (and then posting failed prints on the web). So at this time it sounds like those materials will not be available on the M300 for the foreseeable future. I understand why, but disagree with the decision as I think the value loss is huge and I think there are simple solutions to guide people to not print certain geometries.
Also note another material probably coming to the M300 (PLA based), probably earlier first half of the year.