I would swear that when I first got my Surface Pro that eduroam would work. It wasn't until I upgraded to 8.1 a few days later that it started giving only limited connections.
I've just taken the drastic measure of reseting the Surface back to its original settings and sure enough, eduroam works now. So something has been broken between 8.0 and 8.1.
The driver that I have working is dated 25/1/2013 version 14.69.17062.87.
Have you tried rolling back to that driver (if that's possible) on 8.1? That's what I'm going to try when I have time.
edit-
Just updated drivers to 5/3/13 version 14.69.17064.93 and these work with eduroam too. Haven't upgraded to 8.1 yet.