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It works for me. I have it set to Firefox. I do not get mobile sites anymore.

It worked somewhat for me as well. There is a site I use for work and changing the user agent doesn't allow full access to this site, however I can fully access the same site using photon browser on iphone 4s with Firefox user agent.
 
If anyone is interested, here's a quick test I threw together to show some the methods I know of for detecting mobile devices. It is in no way complete, but it should give a good idea of the methods available.

http://www.tateu.net/mobile/detect.php

and the source files:
http://www.tateu.net/mobile/detect.php.txt
http://www.tateu.net/mobile/normal.css
http://www.tateu.net/mobile/small.css
http://www.tateu.net/mobile/verysmall.css

My guess is that most sites just use the http header value for UserAgent, which can be fooled by UserAgentFaker and Atomix Broswer on an IOS device.

But if some of them use Javascript and/or CSS techniques, I don't know of a fully working method to fool them.

Safari with UserAgentFaker fails to fool the javascript detection test for navigator.userAgent, navigator.platform and screen.width and the CSS detection test for media screen max-device-width on my iPhone and iPad.

Atomix Web browser fails to fool the javascript detection test for navigator.platform and screen.width and the CSS detection test for media screen max-device-width on my iPhone and iPad.
 
A new version is out. It now also changes the user agent string for javascript navigator.userAgent. This should allow it to fool a lot more sites, but not all of them. It still does not change the javascript value for navigator.platform and screen.width or the CSS media screen max-device-width but neither do any of the desktop user agent fakers that I have tried.

I posted a link two posts up that will show you what values it uses.
 
A new version is out. It now also changes the user agent string for javascript navigator.userAgent. This should allow it to fool a lot more sites, but not all of them. It still does not change the javascript value for navigator.platform and screen.width or the CSS media screen max-device-width but neither do any of the desktop user agent fakers that I have tried.

I posted a link two posts up that will show you what values it uses.

New version seems MUCH BETTER, especially on my iPad. I am no longer getting the "mobile" version of ebay on iPhone or iPad. iPad still displays mobile Amazon but that site is pretty fairly useful anyway.

Not sure who makes this tweak, but thanks for your work on it. I should be the one deciding if I want a "mobile" or "full" site. I don't want the site deciding for me ;)
 
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