Great article.
I am having the problem described above where the underlying component is version 1.0.50.0, but the designer is trying to load 1.0.49.0. Any ideas on how to force VS to load the current version? I used to be able to simply rebuild the underlying assembly and the problem would be solved, but since I moved to 64bit, this strategy no longer seems to work.
(Attached to Article Troubleshooting a misbehaving designer in Visual Studio 2010 in Tips & Tricks)