Yeah certainly nice and light for a big tent.
- I imagine with no vents, three people and a mesh ceiling there could be a bit of a condensation problem.
- The mesh would make it cold and not great for powder snow and dirty/dusty sites, depends on where/when you intend using it, as well as how warm you sleeping gear is. I mean with a warmer sleeping bag the cold drafts wont matter so much.
- Wouldn't worry about the 1000mm, I personally would like it higher but lots of tents seem to be around that mark these days with no complaints. Never tried one myself.
- Yes the pole configuration doesn't look fantastic. Although it does have guy points on the sides that will help, it certainly isn't fantastic.
Personally if they could knock about 25% off the weight of the Mutha Hubba HP (like they have the Hubba Hubba HP) that pole configuration (and vented fly) at 2.3kg would be a better compromise in my opinion.
Have you considered the Tarp Tent Scarp 2 (if you're after a roomy 2 man) or the Hogback for a proper 3 man (actually 4). Cheaper and lighter, but with their own drawbacks depending on what you want.