Great! But beware of bug with TMP Rated 5 out of 5 stars
If you use Tab Mix Plus on FF 17 and it doesn't get disabled (since it's not compatible), you may find that a search in Omnibar to erroneously try to open the search term as a url (website). You should disable TMP until it gets updated.This review is for a previous version of the add-on (0.7.16.20121026.1-signed).
Interestig. I am currently using 16 and nightly (19) and both of them work fine. It could be due to a setting or an incompatibility. Can you test Omnibar in a new profile?
Edit: Will check its conflict with TMP. Thanks.