I would ask myself what does it do that other more easily accessible and cheaper rounds can't do. Second what is your intended use of this rifle? For a SHTF rifle it's best to use an ammo that can be found at any wally world or podunk bait store rather than an exotic caliber that can only be found in specialty stores. With a common caliber like .223 or 9mm there is a high probability your enemy will bring it to you.

A few years ago the .300 whisper was the new kid on the block, it's now obsolete. If you really want an AR in .30 caliber it will most likely be cheaper in the long run to go with an AR in .308. I guarantee that round will still be plentiful in 25 years, I'm not so sure about all these other new kids on the block.