One of the neat features about having a solderable breadboard layout on the ATLANTIS is that it allows you to stack additional proto boards using rows of pin headers which can in turn be used to mount additional devices - for example a full size Raspberry Pi or Arduino.
In the case of a Raspberry Pi you could use something like this Raspberry Pi proto shield. Dual row pin headers can be used for extra stability when soldering the hat to the ATLANTIS and then the RPi can simply be mounted off the proto shield from the corner screw hole mount points - perhaps a neat way to mount an MT32 Pi next to your MiSTer FPGA.
So yes, an ATLANTIS for MiSTer will double as a Mini-ITX carrier board for Raspberry Pi :)
Til next time, have a great weekend!