this is a pretty ignorant statement. It is based on the Val movements, but they customize it so much, that it is almost considered their own movement.
79350 chronograph such as pilot's watch and port chrono are both BASED on Vaj' 7750
But what the diff' they make
1. Second dial is modi' from 9' to 6'
2. No hours counter dial
3. No day and date
4. 79350 has 31 jewels 79320 has 25 jewels
To move the subseconds dial might be just fror aesthetic reasons, but that requires reworking the entire movement and adding parts. That is the reason that there's six more jewels in the 79350. That reworking significantly increases the cost.
"Based on" means just that, i.e. IWC looked at the design of various existing calibres and based their new calibre layout on the design of the 7750 because they considered it delivered what they were looking for in terms of power, strength and reliability, and they had neither the intention nor any desire to reinvent the wheel. The movements are still assembled in-house at Shauffhausen by hand.
More info on the IWC 7750 based movements here: http://www.timezone.com/library/comarticle...681571896618891
Besides, the 5001 is almost twice the price of a port auto. There are many many big companies that use modified movements cost as much if not more than IWCs.