I use it in Nuendo. I can only think of a few "gotchas" right now.
1. If you use Folder tracks, and the Folder track is closed, it occasionally loses sync with Nuendo. In other words, the active track in Nuendo might be different from the one that's displayed on the Tranzport.
2. Communication is not entirely bi-directional. If you select a track in Nuendo, the active track does not change on the Tranzport. I thought that I read somewhere on Frontier Design's web site that they're working on this, but I can't find it now.