No doubt they're higher in the middle. I just haven't seen any A arms take a hit there that the zbros would've cleared. More of a gimmick in the sense they're selling you something you don't need than that they're lying about the extra clearance.
I could see that feature being useful on a side by side or atv, for rutted trails and what not. Just don't see the benefit on a sled.
The extra clearance on a sled seems to benefit me the most when boondocking and sidehilling, the double taper or extra clearance makes it so I push a lot less snow than a single angle a-arm (I can track my line and not wash out) and I'm able to roll over so many things the other front ends can't (for every 10 tight spots, the other front ends get stopped 1-2 times).
That's my experience anyway. The double taper for an atv or sXs is more obvious than a sled but once you see how much less snow you push and you don't get snagged but your buddy does, it's noticeable.