I have never used this cab with a tube amp so I can't comment on that. I use mine with a tube preamp and a solid state power amp. My gut tells me an NV would work better with tubes, but I have nothing to back that up with.
I can comment on the form factor though.
I have a number of good sounding cabs (IMO) and the GS412 is my go to cab. Even though it is the biggest one I own, it is also the easiest cab for me to move. Perfect balance and height. It is about 20 lbs heavier than the cab to the right of it (NV 215 in picture) yet it feels about 30 lbs lighter. I also own two GS112's, which are much more work to move around and load up than the one larger cab (neck problems).
Not sure if you have had a chance to hear the GS112's but IMO the GS412 sounds a lot better. It has all the heft in the low end that you would expect but is more balanced from high to low.