16..
I have a review on this board that I did earlier in the year, if you look it up, it will probably answer some questions you have. But all in all, as far as glass and ranging performance, it is the same as the 2400 ABS. What you give up are the tech around workflow...so no on board environmentals, AB ultralite instead of full Ab etc.
What you gain is BT connection to a Kestrel or Foretrex 701 so you can make use of full AB that way. And if you decide to buy a BDX scope, that connection works very well and makes a very fast workflow for hunters.
There are a few other differences, but it's a pretty nice way to step into the system and take it in bites rather than having to make the full investment all at once. AB ultralight is pretty good, and if you are connected to the app, you can either have it updating environmentals automatically for you or you can do it manually. AB ultralite gives up the ability to consider higher level forces like coriolis etc, and uses G7's instead of CDM's, but those things really don't come into play so much in the midrange, more the longer range where AB ultralite no longer provides a solution.
One thing that will be critical is that you map your sensor to reticle alignment. Sig allows the sensor to actually extend outside the reticle as long as some of the sensor is inside the reticle. This is one thing that I wish they would change, but once you figure out where your sensor lies, it works fine.
Not sure what you paid for it, but overall, it's a good unit with lots of expansion room and the capacity for users to expand out with the options they want at the budget they can afford.
HTH!