celendron asks above:
"Is this fun (storage speed) now required or is it merely a premium feature? Depending on how speed sensitive our brains are, some of us see this as a subjective question while others have closed the door on HDD boot drives."
I would say that beginning with Mavericks it -is- now a "requirement", IF you want a computer that works faster than you do.
Mavericks, Yosemite (and probably El Capitan) will -run- on older Macs and newer Macs with HDDs.
BUT ... the user experience will give the impression that the OS is "walking", not "running"...
I want a computer that is
"faster than me"....