In 0.99.113.2-beta, uninstalling and reinstalling the extension now seems to force to to reload properly, at least in the couple of extensions I've tested so far. However, clicking the reload button still does not work.
Correction: content scripts are reloaded when uninstalling and reinstalling the extension, but background scripts are not. That still requires restarting Orion.
Correction 2: Actually, maybe unloading and reloading the extension is enough to get background scripts to reload too. I've just tried that three times now and everything reloaded. In one instance though for some reason I had to restart Orion.