I know that my answer does not directly address the exact question which the OP asked. But you may find my point of view on the question helpful.
I have fired numerous .44 Mag rounds through S&W N frame revolvers with all barrel lengths from 2.5" to 8.4". I've also owned and fired many rounds through Redhawks and Super Blackhawks. All of them shot well, and all are fun to shoot. All are high quality revolvers, and I like them all. I have also carried S&W 629's in all barrel lengths from 2.5' to 6.5'' in a belt holster while hiking or hunting all day in rugged mountainous terrain. I've only carried the 7.5" length Rugers.
It is my observation that none of the barrel lengths shorter than 4" offer any practical advantages at all when compared to the 4" barrel. True, the shorter barrel will save about 2 or maybe 3 oz. of weight, but you will never notice it when carrying the revolver in a belt holster. In addition, the 4" barrel revolver is just as quick and convenient to draw as a 2.5" or 3" barrel if you are using a well designed, high quality belt and holster.
In my experience, almost all shooters shoot the 4" gun better than the shorter ones, even if they like the shorter ones better. You will also get a little more velocity and a little less recoil and muzzle blast from the 4" barrel. And the 4" barrel model usually can be purchased for a lower price. So for shooting, practical use, and convenient all day carry in a belt holster, a 629 with a 4" barrel is as good as it gets. The Ruger confers no practical advantages over the S&W, so I prefer the S&W for its smoother action and trigger pull.
Similarly, I see no practical advantage in getting a Mountain Gun rather than a standard 629 with 4" barrel. The weight savings with a MG is negligible.
Ruger and S&W have both used various marketing ploys to convince us that a .44 Mag snubby is somehow better to carry for bear defense or for survival scenarios. It's just another way to sell more guns. But a .44 Mag revolver is a bulky and heavy revolver regardless of barrel length. The slight savings in weight with the shorter (than 4") barrels confers no real practical advantages.
But if you are a collector, and you want to own examples of all available barrel lengths, then go for it. Or if you just like the looks of the shorter barrels, buy one and enjoy it. (I think they look kind of cool myself.) But you won't get any real practical advantages with the shorter barrels in .44 Mag.
The .454 with a 4" to 6" barrel (if you can find one) will also be a better shooter than one with a shorter barrel.