No offence here! Finally is just a question how they dice the wafers. Maybe it would be even wise, to have 4 dies 25 GH/s each in Multi-Chip-Package. But as you said, in sum they probably will have 100 GH/s per 120mm2.
Funny detail, the minimum count of wafers one can order at a foundry is 25 (1 lot)!
It's really a good question, why invest another $1.5M - $2M for a new 28nm full mask set for gen 2 ASIC if you dominate the market with gen 1?
Because Gen 1 is purely a rough draft to reach an ASIC race goal.
The chips will do their job, albeit be crude and unrefined.
This chip design is all about minimising risk and playing safe whilst delivering in a timeframe that meets ROI for their crowd sourced investors.
It's literally a prototype that future revisions will expand upon, of which there is a lot of room for improvement.
They couldn't achieve this without pre-orders, and what customers want are ASICs and quickly. So that dictates the design priorities. Likewise the window for opportunities for requesting pre-orders by start-up ASIC manufacturers and resellers closes after this has been achieved, much the same as competition from non-professional engineering firms like Butterfly Labs, as the benchmark will have been set if KnC realises their ambition and will require genuine specialists to compete successfully, therefore securing a more competent and professional mining landscape for all involved in Bitcoin mining hardware...
Also because as Johan and Sam have both said at the Openday Marcus and team are perfectionists which is why they had to be so hard on them with respect to timeframe. September is the priority. Marcus is not happy with his design, it will work, but not optimally as he would like. So after this first run is out the way, they get to let him of his leash...