I couldn't agree more. The model of trying to support 3rd party extensions but not having full compatibility puts Orion in an awkward position. I would consider creating a Vimium replacement for Orion but where would you publish it? Firefox store? Chrome web store? Seems like you'd just have to distribute it as a zip that the user would need to manually import and manually update.
Besides Vimium, I generally experience enough bugs with other extensions or the browser itself that I just wind up not using Orion, despite following development for many years now.
What they're trying to achieve with Orion is very admirable but they simply don't have enough resources to pull it off. Making a browser is hard, making a cross platform webkit browser is even harder, making a cross platform webkit based browser that supports Firefox, Chrome, and in some cases Safari extensions is yet even harder.
Agree, either Vimium or Tridactyl or some other form of proprietary Vim bindings. Nothing feels quite as bad with browsers as programming with both hands on keyboard, poppping into the browser for a quick search and having to quick on stuff