Originally Posted by
sinister
Define what it's for.
If you want a lightweight carbine that you only need for survival application (say waterproof shrink-wrapped and placed in an ejection seat kit or as a bail-out weapon instead of just a pilot's pistol) then it has an application.
If you need it for constant shooting and training (to include swimming and SCUBA over-the-beach or ship boardings) you could probably continue to use a MILSPEC weapon and rotate them out as they wear and hit service life.
It's just another machine. The manufacturers and builders are going to market it to people who want (and very possibly need) something different.
Is it worth it for a few ounces?