I've been playing around with your example, and I cannot find any problems with using RouteUrl with special characters as you describe above, at least not in my test environments. The RouteUrl method encodese the urls correctly, and the controller gets the value in decoded form without any problems or deformities.
I've tested this out in IIS 7 as well as the VS 2008 development web server.
Can you provide more complete sample code?
Stephen M. Redd
2009-10-07 05:57:15