If you only use good quality Cotton, watercolor paper, this type works really well. Even damp, I've seen no problems so far with removing the type. However, when I use some on some inexpensive, non-cotton watercolor paper to do an experiment, the situation was very different. When I tried to create and horizon line with the tape to experiment on a sky, using considerably wet paint. I had a great deal of trouble trying to peel off the tape. There was massive amounts of paper, separation, removing the entire top layer of the paper with the tape. This wasn't particularly a problem in this particular case because I was only doing an experiment, but had this been me working on non-cotton watercolor paper for a project that I really wanted to keep, it would've been a total disaster the paper was only slightly damp when this occurred. It possibly might work better completely dry although I doubt it, but if it's even better, I think it would be even worse if it is a disaster.
So far, I say that for high quality cotton paper where you let the painting dry completely before removing tape, you're fine. But if you intend to use it on something that's not cotton paper then beware. It might work better completely dry, but I'm not sure at all that that's going to be the case.