Okay, so a basic rundown on Leica ballistics. Basically, it takes temp, pressure and angle of shot into account to give you a shooting solution. On all Leica B models, you choose your sight in distance and then choose from 12 different presets...these are limited IMO, and I found them only useful to about 600ish yards, after that, things started to diverge. This will vary depending on how far from the closest preset curve your curve actually is....mine was almost right in the middle of two curves, so it had maximum error...so YMMV depending on your ballistics.
However, on the newer B models, like the 2200, you can also input an SD card with a custom curve that you generate on their site. In my experience, accuracy improves dramatically in terms of your solution by using the custom curve, even though it uses G1's only. When using a custom curve, it will give you a solution out to 1000 yards, and the new ones (including the 2200 IIRC) will do it in MOA if you like.
So how does it compare to a Kestrel Elite...in my testing, I found that the base data was very close....that is....pressure readings and temperature agreed....initially. Temperature was the problem, and the drift is exhibited with all of these devices....Sig, Leica, Kestrel etc. That is, if you are in a warm car and get out into the cold, your reading will be wrong for a while, quite a while in many cases. Conversely, if you take your device out of your pack and hold it in your warm hands or set it in the sun or whatever, your reading will climb and be wrong. I have sat and watched the readings climb and climb until they were 10-15 degrees off of the initial reading. Others have reported even higher disparities. With the Kestrel, they know this already, so they instruct you to clear the sensor by swinging it around by the lanyard and then immediately lock the reading. Easy and quick. But the RF/weatherstation combo devices don't have this clearing capability, (though you can lock, but not clear, your reading on the 2400 ABS IIRC, but it's not easily done IMO and useless if you are going from a warm truck to the cold, for example).
How much does it matter....depends how far you are shooting and just how extreme the difference is.....stepping out of an 75 degree truck into 10 degree weather...and quickly taking a loooong shot....yeah, that might be a bit of an issue. Likewise, sitting out in the sun for an hour letting the thing heat up...could be an issue. Whether that matters to you, I can't say, but it is a consideration. All in all, it means that if you are shooting very long where a temp disparity might matter to you so you want the temp to be absolutely right for your solution, the Kestrel is the best choice at this time for that role.
That aside, the other thing Leica's current ballistics don't do, and one reason they limit the distance for their solution, is that their solver will not take into consideration higher level forces like coriolis, aero jump, spin drift etc. In this way, it is just like the AB lite solver in the new Sigs, which also limits the distance of your solution. At mid ranges, this isn't really an issue to me, but some don't like this.
So as far as accuracy of your solution, if you are in a situation where these forces are insignificant (either due to distance or conditions/direction of shot etc.) and that temp has not drifted or has drifted equally, Leica's solver is actually pretty much right on (assuming the use of a custom curve of course). When I tested mine against my Kestrel, which was loaded with a custom drag curve, they were within .1MOA of each other all the way out to 1000 yards, with the before mentioned stipulations.
I would say the best way to understand Leica's ballistic system capabilities is to consider that has been around for a while, and is geared to the hunter that shot long when long was not as long as we think of it now. It is good at what it was designed to do...provide a fast, solid solution to what many would now call mid range shots in hunting conditions, and this, IME, it does very well. However, if you are looking to use it for long range, a Kestrel will provide better ballistic info at those distances.
I feel your pain about the multiple devices...I run binos/a 2700b/Kestrel Elite. When out hunting, it's all in an AGC pack on my chest, so no biggie carrying it all, but man, it would be nice to have one device to range, read, dial. Just one. Thats a great workflow. But honestly, when it comes to hunting, I am kinda there with my 2700....that is...I find it's ballistics, even with the temp issue, being plenty fine for the length of shots I personally would take. Coriolis etc really is not a factor at my personal hunting distances. Other people, that's not the case....but in those circumstances, I think you have plenty of time, so the separate device workflow is not really much of a factor. There is one other thing to consider with the 'all in ones'....and this may only apply at my modest tax bracket...and that is....electronics fail or are superceded a lot faster than optics performance. If I can split out the breakable/or 'will become obsolete' electronic portions...then I only need to replace that one part instead of all of them.
That said, if you got the money to upgrade/replace as needed/desired...there is no arguing with the speed and superior workflow of an all in one.
TMK, at this time, there is no one device that can actually do it all at top shelf levels....that is, no one has a bino with full integrated AB. Sig has a bino coming that will pair to a Kestrel, offloading the heavy lifting there when you want the full suite, but having a lite version (akin to what Leica currently has) onboard if you leave your Kestrel behind. I would bet Leica will not be far behind with a similar bino, but that is supposition on my part.
Hope that helps, if you have any other questions, glad to try and answer or get answers for you. BTW, still on the table to spend some time chatting with them about their products, plans, philosophy etc for a short write up sometime, hopefully!, in the next month or so, so if you have any questions, toss 'em my way and if it comes off, I'll add it to the list and ask.