As this is an APU case, I think the case at a minimum should support the Wraith Stealth cooler that comes with the 2200/2400G.
This will help keep cost down when adopting your case and will likely attract more users the way I see it. This also implies support for other cooling configurations, which is a big pro. It already requires an investment in a picoPSU, so you might not want to force the user into investing in an aftermarket cooler also. I'm guessing this implies support for HDPlex 300W support as well, but I'm not 100% sure on this.
With a case this small, I think a front I/O-less design is favorable because
- you have very easy access to the rear anyway
- it reduces a lot of cable clutter inside the case (this is a big pro)
- keeps production cost down
- it looks really good.
I'd also be interested in seeing this case in a mini-tower form factor, something akin to Lazer3D's HT5 only downscaled. This would mean stretching the width of the case, putting the PSU below or above the mobo, instead of in front.
Using this configuration you also bring some flexibility to the case - like the previous posts state, fan support could be beneficial. Maybe this additional space could support either a dual SFF fan setup, or an internal power brick, depending on the users use case?
Edit: Just checked, if you designed the case with Wraith Stealth support, that does indeed also mean supporting the 300W AC-AC. This could possibly be replaced with 2x 40mm fans if the PSU was positioned below the motherboard.
Are you planning on actually going to production with this case?
I'm going with a modular front.
Not going to put psu below, as it wastes space.
I am planning on production.
Fan support? I'll work on it....