Ignore those guys and get the 1.25. Running an adapter just extends your rack out further, increases the leverage on the hitch, lowers your max tongue weight, and adds more places to wiggle.
I've never seen a D in person but yeah watching that video doesn't seem like that great of an update. The tilt on the old one which I have is a bit of a pain but not that big of a deal, becomes more of an issue the more trays you add on since you have to reach further under the rack. The pain part is the lever kinda jams a bit and you may have to wiggle it or the rack to get it to move every now and again.