The Grip Pod seemed relatively rugged and robust, however, I was never able to test it myself through IMT movement on a range. Essentially, I never saw the carbine slammed down onto the bipod legs under rugged use. I have no doubt the manufacturer tested this to no end and it must have passed otherwise we wouldn't issue it out, right?
The other reason is the Grip Pod is contributing to a lack of discipline in the ranks. While deployed stop into any major FOB's DFAC. Soldiers left and right push the button, snap the bipod legs out, and just lay that baby down with the muzzle indiscrimentaly pointing wherever they please... Largely a personal pet peeve, but when you're dealing with live ammo every day and you see as many ND's... Ugh...
And, of course, you saw my personal reasons in my previous post about not using FPG's at all due to the increased chance of getting hung up in a vehicle.
To illustrate how I kept my personal weapon, here is a picture of me visiting with some Iraqi National Police. M4, CompM2, Surefire, PEQ-15, and a 3 point sling.