what is the extreme distance that it'll range & how far did you test it?
I got it to a mile against things like a steel gate, 1500 against a wood exterior entry door painted white and a power hub (large grey box) at a large solar array project. The desert area I was in didn't offer any big wads of trees to test the advertised ability. Keep in mind target size has to grow with distance. I had best luck with targets of 2MOA or bigger when ranges got beyond 1000yrds.
And how far did it range quickly and reliably on porous rock, dirt, bushes, tree foliage, and tree trunks? Steel plates are easy for these things to range for obvious reasons. But when I'm hunting, critters are rarely standing next to a steel plate. I know what the Leo 850 and 1200 do so would like apples to apples in the wild info.
Zero problems on moist dirt and grass (barley) that was facing away from me (downhill angle) to 800 with fast reads. It did get a bit sensitive there. When the hillside was facing me I was able to get to 900 on dry fine silty soil but lacked hillsides much further away to test against. As stated above, trees are a rarity where I was able to test the thing at range so sadly I don't have good numbers on trees. There aren't any rocks to speak of so I used plastic barrels that have been roughed to hell and back by bullet spall to simulate porous rock. To 1000yrds I didn't notice any difference in user experience measuring the barrels versus the steel targets hanging 3 feet off the the side of 'em.
It spanked the Leupold and Leica 12's. For a direct comparison I compared against a Leica 1200 against dirt and short sparse grass that was facing me and the 2200 beat it hands down at all ranges in speed. The real capability victories started with moist dirt and short grass that was in shadow at 748yrds that I just couldn't get the Leica or Leupold to return on though they would work at closer than 700yrds. At every range the Leica and Leupold offerings we had to compare against also took pretty darned long to give the reading where the kilo 2200 was very fast, nearly instantaneous regardless of range. I have a feeling that if the L's had faster response time that their effective range might be longer just due to reduced shake in the hand giving a more stable reflected beam with less signal noise.
A little off the 2200 topic, but by comparison I played with a new Leo 850 for a few days recently and was quite surprised how well it reached out to 900 and beyond. I have a Leo 1000 and the 2 were always within 1 or 2 yards of each other at those distances. Acquisition and reading of targets at that range was equal.
Leo also has a lifetime warranty. If a unit breaks, they replace it and upgrade to the next higher unit if yours can't be fixed and is no longer made.
To me, the hardest thing about ranging small things at those distances is the inability to see them precisely with only 6x magnification.
I like the Leupold myself, more than I did the Leica for user experience. The Kilo was just so much better in every way though and the Kilo was wickedly faster than either of the L's.
Distance calculation accuracy is based on the speed of light and a timer. The speed of light doesn't change in a medium of consistent refraction index so I'd never expect a substantially different result from one LRF versus another. Minor differences due to processing speed and coding of the computational engine would be something I'd expect to lead to very very tiny differences like those you've noted. The ability to get any reading at all has always been my biggest bugaboo.
The relatively low magnification and optical quality of the viewfinder did present minor issues at long range as noted in the article but having a set binoculars would be helpful for that sort of thing anyway since this is not to be confused with a spotting scope for sure. The optic was quite clear but just didn't resolve fine enough in one particular instance for me to read a target ID correctly where I would have expected it to.
I can't speak to the SIG warranty as I didn't even read it.
All in all, the level of impressed I was with the K2200 is more than I've been impressed with anything in years. It really is quite brilliant and that's not supporterism or marketing hype. I like easy to use things and that was soooo easy to use. It really very well unwound years and years of LRF hate.