Here's my review of all Killer NICs: They're useless. Today's CPUs just aren't hurting for the processing cycles to handle networking packets. At that point, you're offloading work to a NIC-specific processor and gaining little, if any, benefit. Even in WoW, which we all know is highly CPU-bound, this wouldn't provide much, if any, benefit. WoW is highly bottlenecked by CPU speed, but very rarely, if ever, full utilizes all cores, which means cycles are available for network processing.
Yeah, there might be some minor improvement, but the price per performance on these are insane. Killer NICs should be a luxury item for people already running SSDs in RAID 5.