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If you don't use hreflang="x-default" there can be some potential search issues: 1. Searchers of a particular language/region aren't shown a URL tailored to them when one exists. Google might show: www.example.com/en-us/product-item (in Google UK - searcher was searching for example product item) 2. Search results might disply two similar URLs from yoru site, confusin users 3. Search engine might not be aware of all language variations However, if the main index page (www.example.com) doesn't exist and has been 301 redirected to en-us then you can keep en-us as your default page and use . Or, if you've have a URL that doesn't consistently serves content in one language - perhaps it redirects to different language pages based on the user's IP, or it dynamically serves different language content on the same page, or it's a page which only asks the user to select their preferred home page then your hreflang value can be x-default. x-default signals to search engines that the URL's language is broad, rather then specific Hreflang doesn't harm in any which way even if you're using proper redirects

Thanks for your response Oleg. But if I separate matching URLs into different sitemaps, then doesn't that go against what Google recommends by including them in 1 multilingual sitemap?

Thanks everyone. Feedback much appreciated. I think I will go with a separate stylesheet which won't be responsive, but at least give IE8 users a better experience. If I see a high bounce rate or poor engagement with IE8 users, then I will probably add a overlay with browser message. Cheers, Alex