Don't equate S600 with S660 which is just a digital toy. ;-)
No one can find any common design concept at all through these two.
The difference of their drive systems, FR or MR, is only
an inconsequential matter. The most non-negligible issue is what
the original S-series was designed under a robust concept for
PRACTICALITY, e.g. its characteristic chain-drive mechanism
with pushing the differential gear box forward was applied
to achieve a useful large size of boot for any distance journey
in accordance with starting new motorisation age by expressways.
Definitely, current Honda can apply the 'S' pet-name as their wish to
sell their product as much as possible, even for any commercial strategy.
However, due to the point of view written above, the Honda naming S660
must be another company from Soichiro's Honda which had aimed
a manufacturing culture based on the 'MM consciousness'.
Please remind the original concept and I hope everyone to respect it
with seeing S600 without any reference to S660.
No instigating by the groundless 'S' vapour.