The reliability and availability is kind of what makes it a mainframe. That and that you can partition machines on low level. Neither of those this product does.

Do you have some kind of insight on their future product roadmap? As far as I know their next version will just be a new sled into the existing cubby.

It also uses commodity processors and is open software. Totally unlike what we typically associate with mainframes.

So really its not like a mainframe in any aspect other then its not a PC architecture. Its much more like the machines that people like Google or Facebook use.