Xamarin Studio hangs when opening most .cs code windows

Step to reproduce:

1. Open a solution
2. Double click on a CS file which is now opened in the code editor yet
3. Enjoy beachball of death.

Happen on several projects, PCL or not. I read about the XCode/Mavericks bug here and tried to apply the solution posted here to no avail (not even sure it is the same issue).

I should probably mention that I had to delete and reinstall the whole Xamarin toolchain during the weekend, so I'm wondering if I left something behind while doing that?

XS 4.3.0 build 52 (alpha) on Mavericks. Any help appreciated as I'm literally stuck now.