I will be posting a lengthy review, but have been testing it out as much as I can between work and hunting trips. Of course, results will vary significantly based on conditions, but Sig claims, IIRC, 1kish on deer, 1800 yards on trees, and over 3k on 'reflective targets', not sure what that means tbh.
So far, I find that it is very true to their claims, (except for the reflective, have not tested that). I have been pretty consistently able to range trees out to 1800 plus. In bright direct sun, not so much, but hit the right one in shadow and it will do it pretty reliably. Now and then, I have been able to range trees out to as much as 2300 yards, but those are very few and far between, not consistent. Again, conditions and targets mean YMMV, but I would feel comfortable in saying that 1800 on trees in most conditions can be expected, and under many conditions (lower light for example), a couple hundred yards more, with outliers pulling in at the 22-2300 yard range.
As far as the connection to the app, super easy. Handed it to my son and he had it connected and loaded up the ballistics for his rifle in minutes. Then went out and killed an elk with it.
Same with the Kestrel connection. Very rarely, it will not read back ballistic data but if you just range again, it will come. I'd say it's probably 99% or better. Super easy to setup, wakes up and reconnects in about 2 seconds from sleep if the kestrel is running. The one thing I wish they had done is to implement a compass reading in the RF that would transmit target DOF to the Kestrel. It does not, so when using the Kestrel, you will still need to point it at your target and select the direction. The other thing, I have my rifle set for 'mils' in the kestrel, and while the proper holdover numbers come back, they are mislabled MOA. I suspect there is a setting I can change to get it fixed, but have not bothered as I run MOA turrets on my rifles. Only in this one test case, I have been using Mils. Again, the numbers are correct in mils, it's just the label that is wrong. Other than that, so far, it seems to hit all the integration check boxes.
Overall, in terms of connectivity, they have done a pretty good job as far as I can tell so far. Still have lots of testing I will be doing over the next weeks, but overall, pretty impressed with the ranging and very impressed with how consistent and stable the bluetooth connection has been so far.
HTH!