Hi,
in the hpe blade enclosure I believe on the backplane two blades are always joined together in the back so you don't need cables on the outside to join them but im guessing if you have two blades in slots 1 & 2 that are joined in the back you can use a two host vSAN and use the 10GBe cards in the two blades to join them together in vCenter? if that makes sense, so you can have a all-flash vSAN.
matt