Fusion drive is in a nutshell a normal hard disk drive with an SSD core used efficiently so that transparently for the user the response is faster. I think it moves the more used files to the SSD core so that those will load faster, and since they are loaded more often, on the user end it looks almost like an SSD performance. It's a cheaper alternative to a full SSD drive, but does not have the same performances still overall. It's not a bad idea, as far as I would know, for a recording drive because you can have more than 1To for a decent price that perform better than a normal HDD drive, and recording/playback dont need such high performances. The thing is, 1To SSD (normal, not the new PCIe) is coming cheaper and cheaper and it's probably the last generation I would even consider something else than an SSD, because it's more and more worth having a 1To SSD drive. I consider it the major improvement one can do do his setup, over upgrading RAM or CPU. For a recording computer (only) fusion drive could be cool, because the DAW and your most used softwares including VSTis would normally be loaded faster, while still having 1 or 2 To of space left for your recordings. I don't have any personal experience with it. All I can say, is : PCIe SSD is essentially erasing any load time. I boot my MBP in 3s, and wait another 3 so that all my little background running apps are loaded. It's even faster than my phone ! And I'm talking about a laptop that has no space left and is used a lot, so when it was new and not full of apps and crap, it was even faster. Also, the apple 500Go PCIe drive like the one i have, is only half as fast as the 1To one for some reason (I think this one goes over 1Go/s reading speed)