I acquired a gently used Astro-Tech AT72EDII several weeks ago to use for dedicated wide field DSLR imaging, mounted piggy-back on an Orion AG8 with shared guidescope. This is probably pushing my luck for imaging payload with an Orion Atlas mount, but it balances well with all weight on axis. Guiding with PHD2 is still better than 1 arc-sec most of the time.
Waited for Cygnus to rise above city lights fog/gradient for a basic evaluation of the telescope using the North America Nebula (NGC 7000), a favorite summer target. Since the dedicated AT reducer/flattener was backordered, I used the Hotech SCA and T2 spacer rings to get the best edge, going from 55mm to 75mm spacing (i.e. using two 10mm spacers in tandem).
The result looks promising...focusing was solid with the AT72EDII and the Hotech gives an extra degree of confidence in the drawtube. Still using my old Ha modified Canon 450D because it works well and file sizes are more manageable, but I am losing some resolution compared to modern DSLRs or dedicated astro cams.
This image is nearly full APS-C frame with a slight crop for DSS stacking offset and processed in StarTools. Stars are round and pretty good to the edge, so I am happy with the Hotech flattener. Brighter stars have a teeny bit of bloat, but I can live with it. The AT72EDII certainly performs well, and it is a keeper for now.
NGC7000 (North America Nebula)
AT72EDII + Hotech SCA + Canon 450D (Ha modified)
Orion Atlas + Celestron 70mm Travel Scope + ASI120MC + PHD2
3.5 hours total + Flats/Darks/Bias with BYEOS