Jaaph Hi, thanks for choosing SynLink and for sharing the details of your setup!
The Mach1 with the CP4 controller is listed as compatible based on our support for the Astro-Physics GTO protocol.
SynLink supports a wide range of equipment, so it's not possible for us to test every model and hardware combination individually. Even with the same model, actual performance can vary depending on firmware versions and other factors.
What we can assure you is that if you encounter any compatibility issues, we'll do our best to investigate and work toward a solution.
Regarding autofocus for the Heliostar, SynLink already includes an Iterative autofocus method using RMS Contrast. Unlike star-based focusing, this method evaluates image contrast to determine the best focus position, so it may also be useful for solar imaging.
As for your other suggestions, we'll take them into consideration as we continue improving SynLink.