The Topcon X20 will accept NEMA strings from just about any receiver.

The InSight maybe a different story. I have not run the InSight autosteer system, but it uses the Trimble NAVII controller. I have the NAVII with an FMD display. On my system the GPS connects directly to the NAVII and the FMD gets GPS from the NAVII. My comments are under the "assumption" that the InSight system works the same way. The NAVII communicates with the GPS using TISP, not NEMA. In theory, you should be able to use any receiver that can output TSIP with the NAVII, but I have been led to believe that this is not the case. I have been told that the NAVII will only operate with a Trimble receiver. So far, I have not confirmed that. I want to try a Glonass capable receiver on the Trimble system to see if the extra satellites will help with signal loss problems around trees and hedge rows. But the price that Trimble wants for a 442 is ridicules. At some point I am going to try to connect a non Trimble receiver to the NAVII to see if I can get it to work.