I'll post silk pics tonite.
I'd recommend 1 sigma22 per pair of boards. I was thinking "by build" to mean just stuffing the PCBs, as well as some other task, like matching devices and/or helping with procurement of various aspects of the build. We need to consider casing as well, but I'd recommend a one size fits all casing option. I already have some ideas for this. Mounting holes would indeed be the same as Dynahi boards, but I'm only entertaining the off board heat sink layout (see post #1).