ndthwacker,
First, please feel free to PM me if I can help further, I'm going to try and give the cliff notes here to help. I have worked with both Sig and Leica products, have a review on the 2700b on a couple other boards, currently testing out the new Sig 2400 BDX for another coming review, so pretty familiar with the workings of these units.
Long and short on the 2700b.
Strengths: Great glass, very sure ranging under difficult conditions, excellent divergence numbers and laser shape. Onboard environmentals for stand alone use. Can load a custom curve onto the card, into the RF. In these terms, definitely one of my favorites.
Weakness: Ballistics returns. Not only that they are limited to 1k, and there is a reason for that (arguable, but thought out at least). But because their ballistics system was built before distances stretched so far and BC's strayed so much from the G1 model (the only model it uses), it sometimes has to be tweaked to really work well. The more a bullet strays from the G1 model, the more error there is. That said, by tweaking velocity and BC, I've always been able to get a bullet to within .1 MOA out to 1k yards.
However, this is excluding coriolis, aero jump etc., because Leica's system does not measure these. So these can be a factor if you are really shooting long, but out to the 1k limit, I don't think they matter all that much unless you are a really good shooter, which I am not. That said, that is likely the reason why Leica and ABUL limit their ballistic returns past a certain point. They feel their systems are accurate enough up to a point, but past a certain point (whatever they decide), they feel you need the full solution provided by the full AB suite or whatever.
Not as good for bowhunting perhaps, it will not give you just an angle modified range, it's either LOS or full ballistics with chosen curve. IIRC, the minimum distance is 11 yards, which is no problem. Could probably put in any generic curve, but not sure how you would need to set the sight in distance in the curve. I'm not a bow hunter, so have not really tested that, but I am not sure how well this would work.
Temp drift...more on that below.
Sig BDX 2400
Strengths: Strong ranging, though in my experience, not as strong as the Leica unless you are hitting truly reflective targets, then it will outrange it. That said, we are talking pretty solid 18-1900 yard performance in sun on trees in my experience, and longer under better conditions. So it's good stuff.
Excellent ballistics options. They are as follows: Onboard with phone, you load your ballistic and enviro data to the RF (enviro data can also update automatically from the phone if there is a cell connection to pull data from and the devices are paired). Uses ABUL (AB Ultralight) to supply a solution to 800 yards. Does not consider Coriolis etc. Choice 2: Pair to a Kestrel with AB instead. In this case, it delivers range and angle data to the Kestrel, which then computes a solution using the full AB suite, so as far as you can range, it will give you a solution back into the RF. The connection is sure and very quick...super easy to configure and the data flows quickly.
Weaknesses: Optics are not as good as they are on the Leica, but still good, but exhibits some significant flaring and a strong color cast that some people find troublesome. Unlike the Leica, it does not have any onboard enviros, so if you are not using a Kestrel and have no cell signal, you cannot update your enviros with new data unless you just happen to know what your pressure and temp are etc.
When using the Kestrel, if you want to be accurate with Coriolis etc., you have to set DOF manually on the Kestrel. Not that big a deal, but does add a bit of an extra step.
One thing you mention that is definitely true....temp drift is real, whether you consider that an issue or not is up to you. But the Leica and the 2400 ABS with their onboard temp sensors will definitely drift and will take a fair amount of time (one manual says up to 30 mins IIRC) to stabilize to new conditions, depending. The 2400 ABS will allow you to 'lock' your temp so it does not heat up in the sun, but it does not allow you to 'clear' the sensor once the temp is wrong, so warm truck to cold air is going to cause your temp to be wrong for a while. The Leica...can't lock it, and can't clear it. So add to it the 'sit in the sun for a while' and you could be way off (I have been more than 20 degrees off on occasion).
The BDX handles this by offloading the temp etc. to another device. In the case of the Kestrel, it too will exhibit drift, but they solved this by leaving the temp sensor exposed and instructing users on how to 'clear' the sensor and then lock the temp reading in(super easy and quick to do), so that you are not effected by 'warm truck to cold air' or 'sun heated it to death'.
You also mention the 2400 ABS....it has the same optics and ranging engine as the BDX, but does not connect to a Kestrel...of course, some would say it does not need to as it has onboard full AB etc. While it costs a bunch more, it's not really any more expensive than a BDX or 2700 plus a Kestrel. In the opinion of many, it may be the best way to go, as it is fully integrated. Push button, get a full solution. Others are concerned about the temperature problem, or want a better wind solution, or would prefer to split out their expenditures, making for cheaper upgrades in the future. Different opinions for sure, but it's definitely one you should consider depending on what you value, and the relative strengths and weaknesses of the systems.
Believe it or not, that really is the shorter version, but not as short as I intended! Still, feel free to PM me or whatever if I can answer any questions for you.
