The math tells the whole story.
The pro 155 has 2325 square inches of track for 417lbs = 5.6 sq inches per pound.
The Mountain Horse LT kit has 1712.5 Sq in of track divided by 320lbs (610 berg) = 5.35 sq in per pound, so pretty close in the flotation department.
Power to weight ratio is another story.
155 pro - 417lbs divided by 145HP = 2.88lbs per HP
LT MountainHorse on 610 Berg - 320lbs divided by 65HP = 5.35 lbs per HP
The Mountainhorse needs to have almost 115HP to have the same power to weight ratio as the Pro RMK.
A track with a stiff 3.5" lug in the center(6" wide like a moto tire), 3" lugs on the sides in a nice domed curve to make the bike corner and sidehill easy, plus a ski that trails exceptionally well and does a better job of keeping the bike up on top of the soft deep snow, plus a motor making 95HP+, then I'm in. Until then, I can't be convinced.
I understand the math and your reasoning but believe you are missing the whole point of the snobike. Weather some of you want to believe it or not the snobike has a lot of advantages over a sled and of course vis versa, and yes I am speaking from experience with both. I see the snobike as a great tool to access places in the backcountry that a sledder can't or would never want to take their sled. Snobiking gives you more freedom than a sled ever will and Timbesled nailed it on the head saying "Anywhere you want to go" and for the most part it's the truth. Different strokes for different folk. I do believe the snobike is here to stay though.