1500 will be better for transportation to the Outpost parking lot as you are on the Yellow Line, and it's a direct shot from 1500 pickup with only one stop at 1600-1900 before heading straight to the outpost.
2000 will be on the Purple line, and going to the Outpost bus stop, you will be going through all of the cabin loops and making several stops there. More of the cabin folks seem to ride the buses, so more stops, and more ECV pickups through there also.
