Shaun
We do not know how much old code has to be fixed or removed as upgrades are implemented. I could imagine where over a million lines of code has to be reviewed.
The pace may be directly proportional to the price of Vectorworks, not sure? The Vectorworks price may be in direct proportion to the amount of engineering resources that can be made available, wonder how many are working on the application day in and day out. Best I can tell ArchiCAD's new Teamwork server has taken over 4 years to implement for just this one new feature.
Imagine a the amount of effort it would take to manage data if you worked in a file with over 10,000 classes, 10,000 design layers, and 1,000 references to other files. From working in other applications similar to Vectorworks, the present path that I see they are taking will allow greater creativity in creating forms and shapes of all types.
From the Downloadable brochure one see 80 new or improved tools and features. ArchiCADD had maybe 20 in this release, hard to tell as they did not list much. Revit had a very limited set of improvements besides the Ribbon interface. If this were a race, which it is not, I can see Vectorworks overtaking the other two by 2012 as being the most designer friendly application to use for design professionals.