As far as I know and read, no. The only differences are regional keyboard layouts ... umlauds, regional characters as in italy, germany, france, poland, etc. Anything else, hardware and software related is exactly the same. I am also considering purchasing an US version and I tried to search for the advantages and disadvantages of purchasing an US version of the phone. The only differences remains the warranty and those missing 11-13 channels limited by software. I don't see it as a major barrier.
Once again, could anyone tell what is the spread of 11,12,13 channels in wireless networks in europe?