Hey Hamilton,
I just saw this. Been working on a review of the BDX scope/integration, but have some up on the two Leica B model CRF's, and also the 2400 BDX on this board. Read through if you like and perhaps will answer your questions on the functions and differences.
But to answer generally, the 2200 does have AB Ultralite onboard. It does not have onboard environmentals, but when connected to a phone, it will automatically pull that from the nearest station, or if there is no cell service, you can set environmentals manually. You can also load a custom curve from the phone to your RF, which is what Ultralite uses to calculate your solution. However, ultralite differs from AB elite in that it does not use CDM's, but G7's, and it does not calculate coriolis, spin drift, aero jump etc...into it's ballistic returns. Consequently, it is limited to 800 yards for a ballistic solution.
If you step up to the 2400, it's pretty much the same, except it adds connectivity capabilities to a Kestrel 5700 or Foretrex 701 running AB Elite. In that case, when they are connected, the external device does all the solution calculation and then displays your solution back into the RF pretty seemlessly.
In the price range you have stated, ie $500, I'd say try and add a bit and pick up the 2400 if you plan to shoot long. The downside to that is that you still would need a Kestrel if you want the whole thing to be seemless, but for shooting long, it's worth it IMO. And you could make that purchase when you are ready, does not have to be immediate. The other alternative is the 2400 ABS which sometimes can be found for the 8-900 range. But you have to be on the lookout. In that case, AB Elite is integrated as are environmentals, but you have to make that purchase all at once and there is no connectivity with the scope.
BTW, the scope connectivity, in our tests so far, has been excellent, very fast, and good to the 700 we were able to try it out to.
HTH, if you have any questions on these, feel free to reach out if I can be of help.