I bought a Rainbow Astro RST-135 because AP currently doesn't have a compact mount that matches the size and portability of my Stowaway.
My overriding passion is for solar eclipse travel and occultation travel, two activities that don't require long exposures and extreme tracking precision and my 1100GTO and Mach1 are just way too much hassle for me for airline travels. The RST-135 and Stowaway fit solar eclipses perfectly, and the RST-135 and C11 with Hyperstar fit occultation travel perfectly.
But I have to say that now I have the RST-135 I have learned the value of super-lightweight portability. It is so much easier to get out and go for casual stargazing with buddies than with my bigger setups. I may only be 63, very strong and in good health, but even my Mach1 is often more of a handful than I want to haul out for an evening's casual stargazing on short notice. The RST-135 is so lightweight and compact that my entire mount kit, plus Pelican case is only 35 lbs. And that even includes a carbon-fiber tripod.
I am really enjoying my RST-135 but I would sell it in a hot minute if I could buy a compact AP mount for my Stowaway instead.
Abs encoders would be cool but not required by my applications. However I wouldn't balk at the extra cost for them. Personally I would want servos over steppers for a whole-multitude of reasons, although I understand that steppers are quite a bit cheaper than precision servos. Servos have way lower power requirements and consequently give off way less heat. For me that also means less battery capacity to haul around.
Maybe call it the Mach-10, for how light and fast it will travel the world with me.
However my favorite name for it would be the AP Intrepid. Fearless, nimble traveller and adventurer.
"My advice is always free and worth every penny!"
And not just older people, but young enthusiasts who just want a lighter no-fuss mount that more easily travels when going on a group road trip where you have limited space for the Astro gear along with clothes and other travel essentials.
A real question is what is the smallest mount that would work with a AP105 and have encoders? You might not save production cost over a mount that handles a C11 or AP130EDT — but if the mount is dramatically smaller or lighter, it could be interesting.