Witherspoon's status is up in the air at this point, leaving me with a hole I need to fill.

I can start either an LB or a DL in the last spot. Here's what I have to choose from:
Will Witherspoon - If healthy, he's an obvious pick, but let's assume we get no news this week.
Justin Durant - I haven't heard that he ever managed to become the starter. I'd think he would get some snaps, though.
Dan Connor - It's not his time yet.
Anthony Waters - Looks like Smith got that starting spot while Cooper's out.
Niko Koutouvides - Seems he's a backup 2-down scrub who will be my first player to dump on waivers.

Dewayne White - Nice matchup at the Falcons, but it hurts to think of starting a DE in this spot.
I've got some other decent DLs, but none I'd start over White.

So... if Witherspoon is out, do I start White or go with Durant?

I haven't heard anything about Durant either. I would start Durant if he is a starter, if not, White.

Depends on Durant. If he's the starter, I'd consider him. However, the Jags are still alternating snaps/series with Ingram and Durant didn't start the last preseason game. Keep an eye on the Jags sites, but he seems like a 30-35 snap guy at best right now.

White isn't a bad play, particularly if he's at home, with that matchup. If you've got a solid starting roster otherwise, it might be worth going for White's upside.