1. I wouldn't fret not having local Ag Leader support. They have a free support phone line, and their products are easy to use and install.
2. You can build upon your gen 2 on the planter (vdrive). Highly recommend. Could also be used in the combine as a yield monitor.
3. TMX 750???? Doesn't exist. You either have a CFX-750 or a GFX-750, both of which I don't like.
4. my suggestion, Steer with Ag leader, run planter with the 20/20, and use either in the combine.