Yes, Same here too. The HTML Editor + IE9 issue is a pain. But can you imaging building a nice website and CMS only to tell the customer they can't use IE9 because the CMS you just built won't work with it! EEK!
To be honest every release of HTML Editor we've used has had issues and I don't have the time to troubleshoot it.
That's why I'm loathed to buy other plugins here.
Believe it or not, as well as using the new Dreamweaver, we still use CS4 and Adobe Dreamweaver Developer Toolbox, it's an extremely reliable and easy to customise set of tools. I'd switch to the Web Assist products if they were easier to use and more reliable.
The worst thing is that I overcame this issue a few months ago, but I can't remember which site I was working on and I can't remember what I did to overcome it.
Maybe I'll try some Meta tags to force IE9 to operate in v6 or v7 compatibility mode, I'll see if that works.