Hi, I'm the founder of Woobius. Firstly, thanks for your kind words on the user interface. We are fortunate to have Cliff Rowley who been a key driving force behind it.

With respect to the body of your comment. The reason Woobius is useful to architects and engineers is that it fits into their existing workflow - e.g. they produce a 2D drawing that forms part of their legal documentation. While this process is (for all intent and purposes), basic, it's often neglected. Being practicing architects ourselves, we realised that by making this easy and efficient, our collaboration cost can be dramatically reduced.

I believe that once we have achieved this first step, we can start to tackle the more complex issue of allowing collaborative annotation on drawings themselves. Hopefully, by which time we would be in position to annotate a 3D model even!