Also, has anybody in the community had experience of cycling through North/South Carolina, Georgia, Alabama, Mississippi? Is it safe? Is the ride going to be worth the diversion?
Is it safe? It's as safe as anywhere else in the U.S., meaning we have some movie kooks, but no more than anywhere else. You're more likely to have trouble from aggressive or distracted drivers than shotgun-toting moonshiners, chainsaw mass murderers, etc., etc. I think Jim Henson (the Muppet creator) had it right: "People is people."
Is it worth it? Personally, I think the deep south goes from the Atlantic coast 60 miles south of Norfolk (Yorktown), around an arc 90 miles outside Atlanta, west to Birmingham, and up towards Memphis. You'll barely touch it with your proposed route, but you'll have to do a lot of route-finding. You'll be crossing the ridge lines coming northwest out of Atlanta on your draft route, meaning limited routes going over the ridges, often with high speed, high volume traffic.
I'd suggest, instead, taking the TransAm to meet up with the Underground Railroad or Great Rivers route, go south a ways (maybe to Tupelo, or Jackson, Mississippi), then hop a bus to Colorado. I loved riding in Kansas but your imagination can fill in the blanks on the bus.
That said, if you want to ride from Atlanta towards Memphis, check with "yumadons". Suzanne has put together a route through Atlanta, and up to Florence, Alabama that they're planning to try later this year.