Non-History based modeling may have some advantages.
One of our manufacturers uses this (product is KeyCreator)

Check out this "promo article":
http://www.kubotekusa.com/news_...ews/June07/feature2.html

Demo movie
Check out real time editing using dimensions link on the right side of the page.

http://www.kubotekusa.com/technology/real/faces.html

Direct editing like this looks very desireable.
It also lets you work more easily with imported geometry which has no "history".

These kinds of feature auto-detecting/ editing tools would be good additions to Concepts Unlmited.