It's totally doable to run 6000/6500 with insight. If you end up buying a new unit and don't have access to newer display (like Integra or InCommand) have your local dealer set up the 6000 for the insight for you. Takes 5 min with proper cable and an Integra.
Also.....you can use other receivers with insight also. Another good simple unit that is becoming more inexpensive used is Trimble 252 or 262. At one time Ag Leader had their own versions of these units. The insight should plug and play with 252/262 and should be able to configure GPS from the insight set up screens.