I just learned about the existence of Equatorial platforms from the Dutch astroforum where ‘volgplatform’ was mentioned. For a description of the what it is and why it works, please refer to Reiner Vogel’s Equatorial Platform web page. This page also contains links to manufacturs, such as Equatorial Platforms, worth a visit since it illustrates the basic idea behind the platform.
I am not sure yet if I want to build or buy it. I was fully prepared to motorize both altitude and azimuth axes on my flextube, since that would allow me to build a complete Goto system.
Nonetheless the equatorial platform is something I would have myself never thought of and therefore brings new ideas. One big pro over the alternative of motorizing alt and azimuth is, that the equatorial platform is less invasive on the mount, since only the lowest board piece is replaced by the equatorial platform. It would also work in combination with the digital compass I am working on. The compass could provide me with Ra/Dec coordinates as I move the scope manually to a target, then use the equatorial platform for following. Another pro is that with the two-axis variant of the equatorial platform, longer exposure astrophotography would no longer be impossible.
Also interesting is the use of SkyWatcher’s RA motor, apparently motors like these can be customized for other projects.