I've used dry erase quite a bit on cuben. Sometimes it comes off great.....sometimes not so much. I've found that cuben seems to have two sides to it. One side is a bit smoother, while the other side is a bit more textured from the underlying spectra strands. You can't really see the difference, you just observe it when you try to wipe off dry erase marker. Unfortunately, the 'good' side of the material isn't always the same side. Within the same run of fabric, one side can be the smooth side for a while and then it'll switch and the other side is smoother.
What I do is test how easily it will come off by making a few dots in the general area I need to mark. If those come off easy, then I just go crazy drawing all my lines and usually they all come off easily. If it doesn't come off easy then I try the other side and usually that works. If not, then I just use the marker sparingly and rub harder to get 90% of it off after. If you don't apply it too heavily, you can always get at least most of it off. If you use a color that is similar to the color of your cuben then the consequences will be less if it doesn't come off so great.