Ah, I was just reading an adjacent thread about rebuilding ergo levers and Mr Drew_Eckart shows a complete and thorough description of the internal differences between my lever and Ultrashift. I had no idea it was a complete redesign of the internals. It would seem that the Ultrashift version is much more durable without the G springs and spring carrier that always breaks. But what about the feel and shifting? Is Ultra better, stronger, faster....?
And the thread referenced above:
https://www.bikeforums.net/17512296-post18.html