"is not being evangelised as a radically better piece of kit, with the all-flash EF-Series products being shown in the slide above as a faster performer."
If your only concern is raw performance then you're looking at it wrong as far as FlashRay is concerned. The FlashRay is a vastly better piece of kit (or will be when the code is completed) because not only does it offer flash performance nearly as good as the EF series, it also will do everything the FAS can do - the business value and efficiency stuff for which NetApp is famous and generally trounces the competition. The EF series is quite dumb by comparison, so although it performs very well it's a bit of a one trick pony.
It's quite possible today to go out and buy a very fast SAN, but many of my customers are waiting for one which also manages the backups, DR and automation of private cloud functionality, and most importantly fits in with the company strategy which for many of my customers is currently NetApp FAS for these same reasons.
Since I don't work for NetApp the above is based purely on hearsay and speculation, but I believe it's the aim of the platform