Suiseiseki IRL said:
The problem wiht the first is that it's too front heavy with the XM320 attached to it, the carbine suffers from the same problem as every other stump-stocked weapons (i.e. nothing to put to your shoulder while aiming and recoil), and the LMG is just too damn long for its own good. The LMG's barrel and handguard should be on the sniper rifle version.
You sure know alot about guns, but I have to make a note here. The actual MX8 parasniper isn't displayed in the picture. That's just the standard marksman rifle, with an extra long barrel. The parasniper has a different kind of scope, with 3,5 magnification, it looks only slightly different. All barrels are interchangeable so there's no reason why you couldn't have the LMG barrel on the marksman rifle.
If you want a light, comfortable and incredibly accurate sniper rifle, take a look at the SAKO TRG 42. Or if .338 or .300 win mag are too much, the TRG 22. It's an astonishing rifle. I should know, I have two of them.
On topic: I would have the H&K 416K with all possilbe extras available. And an AK series rifle as a backup.