If there is something out there with the portability of the EZ-Guide / EZ-Steer combo, I'm not aware of it.

Moving from tractor to tractor is about as simple as loosening two wingnuts that mount the servo steering motor and tightening them on the target bracket. Then route the cables, sitck the mag-mount antenna on the roof, and plug the power cord into the lighter plug. Once you have the servo bracket made, it probably takes about an hour to do it all up neatly. EZ guys have ready made brackets for the large frame Cats, so that's not a big deal.

Accuracy seems to be mostly limited by the accuracy of the WAAS corrected GPS signal. Steering is usually held within 2 inches or less of where the system thinks you should be. I've only used my system for about half a season & I can't really remember a time when the display indicated more than 2 inches from target line.

Pics of my installs here. I chose to build my own brackets, as I thought I could do a bit better than the EZ guys did.