Hi Erik
As far as the Atlas focuser goes there is no dispute that it is the ultimate in after market digital focusing units if you plan on using anything of any size and weight on any scope system and wish to eliminate the possibilty of flexure - hence why I incorporated it into my fast astrograph from day one:
http://www.pbase.com/strongmanmike20...85837/original
That said as has been suggested there may be issues with fitting it to the back of the Edge HD but if its doable then the Atlas is the best for sure but other robust traditional focusers with robo focus or similar attached should work very well too
Not sure that was all that much help but good luck with your project
