I have tried both the Ziess and the Leica out on Antelope hunts in SE Colorado. Looking at both, the Leica outperformed the Ziess as far as quick and accurate ranging. The Ziess is a little larger and has a larger viewing lens, but the Leica is faster to acquire and much more compact. I have ranged grain elevators to 1080, Cattle to 800 and some change, and Antelope to 770.
Leica states they can spot soft targets to approx 75% of the max distance, so 1000 ~ 750 and 1600~ 1200. I have found this to be true with the 1000.
I have tried the two and sold them as I really only use a LRF during lope season, will most likely get a 1600 this year, even though I will only shoot 700Y or so, I want to be able to "walk them in" and stalk closer.
Pics through a Leica 1000
I was dinking around on a lope hunt a couple of years ago., shot a water bottle at 400 (you can see the other haybail in the distance), walked down and ranged back for a pic.