The real problems are in annotating these drawings collaboratively, merging separate parts and layers of buildings and in general managing the actual flow of information in a design process instead of merely the drawings. Solutions with versioning IFC files, IFD libraries and solving the problems in this area are far more important (and complicated unfortunately). Think like: Which parts of the building were modified in the last version by the architects and how does that influence the building costs? Is the old construction still valid and if not which parts cause conflicts, etc...
EDIT: I forgot to mention that the innovation that woobius does on the user interface side is really great and that they managed to get featured on techcrunch is also great to get more attention to this topic, so all the good to them!