Team Center Express will always be an extra cost to implement the full server-side system, mainly because Team Center Engineering and Team Center Enterprise is UGS' biggest money maker.
I do expect to see Insight starting to go by the wayside, as TC Express is a cost effective strategy with a bigger bang for the buck. Also, TC is completely developed by UGS, whereas Insight depends on Sharepoint and UGS already got bit once by Microsoft radically changing the back-office from Sharepoint v1 to v2, leaving UGS' customers with no easy way to migrate. UGS got bit once that way and its customers were irate, I think they will move away from that dependancy in the future in order to avoid that situation again.
--Scott
For some pleasure reading, try FAQ731-376