I personally find that the Speed Dial helps to adjust the levers to some extent do support both, cantilever and v-brakes.
here is a bit of history on the Avid levers
https://www.retrobike.co.uk/threads/avid-speed-dial-brake-levers-v-canti.471361/post-3489899
To my knowledge, the Ultimate had been originally designed for Cantilevers.
They got later a different internal chip to be able to support V-Brakes, a picture of this chips is at this post
https://www.retrobike.co.uk/threads...vid-arch-supreme-v-brakes.304798/post-2281195
The SD2.0 without "L" had been to my knowledge designed still for cantis.
We have recently discovered that also certain bikes like the
96 Barracuda AL750 had been officially equipped with those 2.0 levers in combination with Onza HO cantilevers.
The ones with "L" than for V-Brakes.