The infamous opinion by Chief Justice Lee we all refer to is really quite dubious in its usefulness as a "standard" of how OC would be viewed. As far as I know, it's never been used as any sort of case law, and I've never heard of it even being referenced in a court case.
A more concrete and worrisome item is the recent AG opinion. However, in my (completely amateur) opinion, it would have a hard time standing up in court if that happened, because it horribly contradicts itself.
All that said, I still OC part-time, albeit with a concealed carry license on hand (it's always in my wallet, as I do carry concealed a decent amount of the time). I haven't directly encountered any law enforcement personnel in Hattiesburg over the last 1-2 years of open carry, but a few dozen people have asked me questions about legalities, my firearm, etc. I have never had a bad experience with OC here - yet.
To get around to your question JC_Biggs, the question of whether OC is "legal" without a Mississippi Firearms Permit (aka concealed carry license) is untested. If you want to play it safe(r), get a Firearms Permit and avoid carrying in the list of places prohibited to concealed carriers by
§ 45-9-101 . (I have no statutory or case law basis for that suggestion, just suggesting a policy that may help avoid trouble with ignorant/power-hungry LEO.)
Title 97, Chapter 37 contains the list of weapons crimes, so familiarize yourself with that as well. Another source for the statutes is
http://www.lexisnexis.com/hottopics/mscode/.