Our company has purchased 4 seats of Inventor 10 - we currently uses ACAD2006 for 2D, 10% of our 3D parts and assemblies are STUCK in Mechanical Desktop, and 80% of 3Dparts/assemblies are in Pro 2001 ----- we have Wild fire, but have not installed it.
(My opinion) - Who copied who? The Pro-E and Solidworks folks will tell you not to buy RE-Inventor, because they copied the benefits from each other. They did enhance the pictorial representation of screw threads....
As I said - we haven't gone to WF yet - because that would probably be a 3-day or 1 week upgrade training for everyone from PTC. Remember - 1 week training for basic - 1 week for detailing, 1-week for advance, 3-days for sheet metal, one week mechanica, 3-days large assembly.......... To be proficient andproductive at what Cost? How many weeks of lost time for training instead of releasing projects? Plus $ for each module. Why go PDM or Intralink --when Vault comes with Inventor?
One week of Solidworksor Inventor training and you can be as dangerous in part modeling and assemblies as some of the us Pro Dinosours.
As for handling older files and to what formats..... you will need to re-do all of your drawings ----- you will have a transfered 3D part/assemblies that won't be associated to a drawing anymore.
It almost depends on the final customers (end users)needs. If they use Inventor, UG, Pro, Solidworks, SolidEdge, Catia.......
If you cross over to the Inventor, SolidWorks...... forums you read their rant & rave. To me - I don't care what platform the design is in - as long as it's in 3D, and has parametric associativity. Just remember that it was us old(Autodesk)Mechanical Desktop users that got stuck!
Depends on your application