HyperTransport != QuickPath

Cray's Seastar interconnect uses Hypertransport and is completely integrated with the opteron memory-hierarchy, Switching to intel's Quickpath needs a major redesign of the entire memory system and low level system calls used in XT.

Quickpath may look better on paper(because it is designed ~7 years later), but it is still pretty immature compared to HyperTransport, at least in the >1000 cores range.

The CX1 is just a motheboard mod (Like Tyan) with a fancy deskside chassis, and AFAIK it only runs windows, has nothing to do with the XT-architecture. It is just an attempt to create a new market.