The thing that makes this long i non-diphthong so culturally interesting is that non-southerners (a.k.a. yankees) consider it a marker of special toothless ignorance. Even the most dull double negative-using elementary school dropout from yankee land feels intellectually superior to a southern fellow who says, "Ih think it's about fihve mihles down the road."
Now, here's the interesting part. When I was growing up I had the same snooty feelings about Southern Appalichian Mountain folks who never diphthongize a long i no matter what consonant follows it. They don't let diphthongs go to waste though, they might diphthongize something else like as short a. Famous race car driver Richard Petty might say, "Ih drihve a faa-eest race core on a track that never turns riht."
I was stunned to learn that I still have my prejudice when I recently arrived here to live. The first thing I did (of course) was break off a tooth. (Probably from chomping on a BBQ rib but that's another story.) Oh mercy! I had to go to a strange new dentist from the yellow pages. Of course I got lost on the way and had to call for directions. I had to report to the receptionist that I was at the corner of Biltmore and Short Coxe Avenue. (I'm not kidding; that's really the name of the street.) She instructed me to, "Go just a little down Biltmore then turn riht into our parking lot." Yeow! At least she was just the receptionist. When I finally arrived and got in a chair, the dental hygienist instructed me to "Biht down on this." I almost bolted out of the chair running. I resisted the escape urge and I got the greatest crown job ever. I've been here a month now and I'm finally overcoming my silly linguistic prejudices. I long ago determined to never behave or think like a racist. Now I'm committed to never being a diphthongist. We're all human beings no matter how we close our vowel sounds. Riht?!