I don't know if my post will give you any help, but I decided to register to this board to answer your question anyway.
I'm in a similar situation as you are, because recently I've started a MOGRE project and I had to collect addons that I'll use. I started using Miyagi, as it's suggested for MOGRE, and I'd probably stick with it if a lightning of obvious idea didn't strike me.
! Think of it: we're all webdevelopers at some point, so chances are we already know the technology behind the webdesign and we know it very well. What's more, there are tons of examples regarding the aforementioned languages and every possible question has been already answered. What's even better - there are tons of free, reusable code and art that are ready for use.
So, I have switched from Miyagi to Berkelium-sharp (it's based on Chromium - an engine that's the heart of Google Chrome). I'm still researching it, but I think I'll have fully functional HTML-based GUI Manager pretty soon (Berkelium already works for me). If you'd like to try it out, there are two great tutorials that'll get you started: http://www.ogre3d.org/tikiwiki/tiki-ind
... ntegration and http://www.ogre3d.org/tikiwiki/tiki-ind
The alternative is Awesomium and Navi, though they are developed under a slightly more restricted license. But I believe Berkelium will be more than sufficient, since I'm not really seeking any advanced API - I just need a web browser engine implemented in my game!
Please note: I'm probably highly biased, since I'm a professional, everyday webdeveloper. Maybe more experienced MOGRE or .NET developers will have some better ideas.
: I'm not sure if I'll have the time to polish my code, but I'd like to make it public when it's finished, so everyone can see how to integrate MOGRE with Berkelium in an example.