Bridgestone tyres, RE050s included, haave so many different homologations for various manufacturers that they are supplied in so many different forms. I think the SO3s had 6 different homologations, and each one performed significantly different to the next. For this reason, I now stay clear of Bridgestone's because of the job I had getting the correct tyres for a Chim 4 years ago. There is just too much left to chance unless you are prepared to wait/and or be charged a differrent price from the one originally estimated.
Different cars handle tyres differently, and different driver's interpret the tyres abilities differently. A confident and predictable tyre may have lower limits, but a less predictable tyre may well have higher grip limits, but because it is unpredictable the grip cannot be used. At higher speeds, it may become so unstable it's limits are never reached by all but the most gifted drivers. Then there is breakaway and recovery characteristics to factor in, so tyres are a very hard thing to measure. Pressure and temperature also play a major part.
I always thought that listening to guys who do trackdays would be the most accurate appraisal of tyre abilities. Then again, perhaps that advice is looking at the tyre in extremis, and the tyre may display traits which discourage such exploration on road.
From that point, I thought Symon and I would largely agree, both of us having extreme speed experience with TVRs. Strangley, he rates Goodyear NCT5s as almost as good as GSD3s, whereas I see the NCT5 is a failry good touring tyre and the GSD3 as a top notch UHP tyre. As I said before though, there are so many other factors to consider.
BTW, Avon ZZ3s had a nice wavy directional tread pattern, and the ZV3s had an angular assymetric pattern. From my experience, it is the ZV3s which are poor in the wet.