You'll have more room for sure in the Kaitum because of vertical end walls and useable vestibules on both ends. It may technically have the same room as the Nallo 3GT, but without the sloping end wall it is more useable space. Especially for your height. You can always tie off to rocks or boulders if need be to pitch. Allaks are nice, but at 6'7" I think you'll appreciate the room of the Kaitum.
The tunnel designs are their strongest tents in the wind. You can't go wrong with any Hille, but there's nothing to be concerned with regarding wind in a tunnel tent. Stephenson Warmlites are another proven all weather tent that is a tunnel design. There's a reason those designs are taken on expeditions all over the world. For two people with one being 6'7", there's no way I would recommend a 2 man tent from any manufacturer.