I am running Yokohama AVS ES10
I am running Yokohama AVS ES100 tires on my 78 GTS and like them a lot. I decided on these after reading the test reports, comparisons and customer feedbacks on Pirelli, Dunlop, Goodyear and Kumo.
The biggest complaints about tires like the So3's were excessive noise after 5,000 miles and tramlining in ruts on the freeway. That and the quick tire wear and the high price.
The Yokohamas are a bit harder compound but seem to retain the same handling characteristics throughout the life of the tire.
It really boils down to the type of driving you will be doing and what you expect out of your tire as opposed to what you are willing to trade off for performance.
I found the customer feedback on the Tirerack site was invaluable, as JR says 'Real World' evaluation.
Thats my two cents.