According to IDC, the vast majority of SSDs sold to consumers are put to use in notebooks. There's obviously a large contingent of desktop users using SSDs to help augment performance. But if you're a notebook owner, there's the added benefit of shock/vibration protection. For many road warriors, SSDs provide more data safety than a hard drive.
There's also the issue of power consumption to consider, since battery life directly affects the time you're able to spend away from the wall. Although it can be argued that screen brightness, Wi-Fi activity, and processing workloads impact run times more than storage, there's a big enough difference between various SSDs that you really can squeeze out more battery life if you make a careful selection.
Our meter stops working when we hit 5 W and above. That's why we're lacking a score for the 512 GB m4.
You'd expect that the SSDs sporting more memory package and dies per package would use the most power. However, that's not what we see in 4 KB random reads. It seems that there's a threshold where adding more NAND chips to a channel actually lets you to use less power to retrieve information (at least when you hit steady-state performance). That point seems to be at 256 GB with the m4. Once we move up to 512 GB, we're back to using slightly more power.