OK, I managed to get a Fusion drive working with a 250 GB m2 SATA drive and a 2 TB Samsung 2.5" notebook drive. However, I seem to have some graphics issues with sluggish performance and changes in Safari tabs' gray shades, and I have lost sound. There is no output option in my Sound Control Panel (I'm connected to a 27" Philips display via miniDisplayPort). Any idea what might be the cause of these? Otherwise, I'm very happy with my 2.25 TB fusion drive!