Wouldn't a better comparison be CM's own 1.0-1.6L Nano Units (150 x 192 x 38mm and 150 x 192 x 59mm respectively). The Akasa/AsRock "270 MxM" case isn't exactly well designed to minimize volume while the CM Mini very obviously is. If we're going to do that, then the CM mini is 2.45x the size of the CM Nano 1.6L and 3.8x the volume of the Nano 1.0L. Furthermore while 1 M.2 and 2 HDDs is nice, I'd personally rather just have 3 M.2 drives. I'm not saying the ITX route isn't a good way to go, especially if you don't need super small and portable to the degree that the Nano affords, but let's compare apples to apples here.
The CM nano can indeed be used for the 270Mxm but the same argumentation is valid. Is potentially twice the price worth it? Do not forget, your facing a few more issues like cooling. With 38mm, your even more height restricted for the CPU/GPU coolers. So forget about putting a 95W 7700k inside that case. Or a GTX 1080, unless you go down the Max-Q downclocked version.
In most scenarios that i read sergiiua has issue with finding a acceptable temperature/noice for the GTX 1060 MxM. We are not even talking 1070/1080...
He needs the bigger 1.6L for a more proper cooling. This 1L case is simply a experiment.
CM Mini : 180 mm x 100.0 mm x 180.0 mm
CM Nano: 192 mm x 59mm x 150
The difference is already a lot less. The big difference being the thickness but that opens up the door off cooling/troteling/max cpu power again
There is a reason why the Desk Mini has 50mm clearance = fan size = cooling capacity.
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The issue with multiple m.2 is simply: What advantage do you get?
A single m.2 pcie gets close to 3000/2000 R/W. This can be your main OS/Games and other applications or files that benefit from large speed.
What does the other SSD m.2 slots offer more? Assuming you have a 500GB or 1TB main m.2, the rest of the m.2 slots will be used more as storage. Unfortunately, ssd/m.2 is still massive expensive and given the lack of flash memory production now ( high demand ) the prices are going to stay high for the next few years. For the price of a single ssd m.2 500GB, you can pick up a slow Seagate 5TB drive. Giving you much more carry capacity.
Lets say we install 1TB PCIe + 2 * 500GB SSD drives in the Z270MxM. That gives you 2TB in small form factor. But you can also buy a single 2TB for almost the same price in any Mini-ITX board ( SSD/PCIe storage price is fairly linear up to a point ). In other words, multiple m.2s do not give a massive advantage in regards to price / storage. Only if you got crazy with multiple 1TB and break past that linear price point curve.
/Giving it a lot of though
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The CM Nano has indeed a market in people who want the smallest of smallest in there pocket and are not looking for maximum performance. But like with most products, its finding the balance between maximum performance with best cooling with minimalist size
