Monitorman - I am a UK user and have had no problems. Despite the different sites Ebay has in various countries, each items auction number remains the same all round the world. The only thing to watch out for is the currency of the auction. The amount you set up for your snipe will be bid in the same currency as the auction itself. So if like me most of your buys are from the UK in punds sterling your snipe amount will be in pounds. If you are sniping a US Dollars auction remember that your snipe amount is in Dollars too.
The only confusing part of AS for UK users is that all the emails you get after an auction refer to the equivalent US dollars amount. You may get an email saying congratulations your snipe was successful for, say, 14.00 but really it equates to just a tenner.