Just like my last post on the FILBE prototype, this pack popped up on eBay and that is still the only place I have seen mention of this pack.
According to the seller this was Gregory's entry for the assault pack component of the FILBE system.
With the strange horse-shoe zipper access into the oversized top lid and the dual front pockets this pack reminds me of a miniaturized Kelty Gila. Also the one piece shoulder yoke isn't a very gregoryesque feature and echos an older Osprey pack or the Mystery Ranch system. The hipbelt might be the most unique feature of this pack, I'm assuming the cut-outs are for ventilation and not for MOLLE compatibility since the USMC-spec MOLLE attachment system would be brutally painful against the body. While the unpadded hipbelt might look uncomfortable it should be kept in mind that every other assault pack (barring the new MOLLE medium ruck which is barely an assault pack) has no more then a webbing belt so any amount of surface area larger then 1.5" is probably an improvement. Also a durable hipbelt like the one above isn't the worst idea for Marines since they tend to shred anything with foam or spacer mesh in short order.
I think the Marines probably made the right call with the smaller, simpler assault pack they chose.