I'm afraid you are comparing two very different things, designed for different needs. Just like the Star Adventurer is meant to be a cheaper and lighter alternative to a classic GEM, this Minitrack mount is meant to be a cheaper and lighter alternative to the camera mounts like the Star Adventurer or SkyGuider. Especially today, as bulky DSLR are in decline and are slowly being replaced by smaller and lighter mirrorless cameras, this kind of mount makes sense.
I see it as a small grab and go mount, easy to set up, that you can throw in your backpack during a hike or when traveling to remote locations. And of course, it's primary purpose doesn't seem to be DSO (even though the product pictures show some), but rather nightscapes, Milky Way shots.
In decline ? Well not (yet), there on only one brand (sony) which has full frame mirrorless which is the A7. Canon and Nikon will follow, and in APS-C there are a lot more mirrorless, but the lenses are still bulky and heavy if you want to capture enough light.
I disagree regarding polar alignment. Again, this mount's purpose is not to make 3 minutes exposures of faint DSO, and therefore, a rough polar alignment is more than enough. I made some nice pictures of Orion and Andromeda with just a tripod and a 135mm lens. And you can make wonderful shots of the Milky Way with just a tripod. So a little mount like this, even roughly aligned, can only give better results.
Three minutes is not that long and when 40' off the poly you WILL get tracking errors with a 135mm lens, particularly when mounted on an APS-C, this will even happen at 1 minute.
And for 30 seconds nightscape exposures you usually don't need any tracking at all, just take more frames with a steady camera and stack them.
Only if you want to make faint DSO images with a 500+ mm FL telescope, then this mount (and the Star Adventurer) is unsuitable.
And a spring driven motor also has a periodic error, it is just a much faster spinning motor with a transmission to one revolution in 24 hours, nothing different from an electric tracker. The energy source has nothing to do with the periodic error.
Anyway, when there is a 'Version 2' of this mount with southern hemisphere support and an optical polar scope, then I am really interested.
Edited by skysurfer, 20 July 2018 - 10:56 AM.