Looks like a match to me then. With most of England, France and Spain being 8's and 9's, that would be akin to the West Coast here. No huge winter ice ages to speak of.
The West Coast has developed another, and better for us, zone guide - the Sunset Guide. For me, without any kind of winter freeze to worry about (normally), summer heat, and lack of humidity are of much more concern when gardening. Sunset factors this in.
I see Moscow is a positively balmy 5 in a sea of 4. Those early Czars must have been gardeners too when picking a spot for a city.
Cheers,
Mike