The Hermes online prices are a little cheaper in France: a swift Dogon is £1374 in France and £1430 in UK ( I did convert euros to Stirling)
You can easily check for yourself by changing the location of 'Find a Hermes store' to whichever country you are interested in and then click the 'buy onlne' option. (Make sure you check like for like)
It is not a huge difference, especially compared with USA prices. (About 4%)
As I wrote above you, if you have specific wishes, buy it where you see it first.
From experience I know that the SAs in New Bond Street and Royal Exchange will search the system to see if what you want is available somewhere else if they do not have it. I'm sure others would do the same.