The Killer Wireless-AC 1550 adapter may be an Intel 9260 chip in the base, but with its own drivers it certainly offers an added value with its own QoS engine, the ability to turn your laptop into an access point and simultaneously use a WiFi and an Ethernet connection.
As far as the added value in performance is concerned, we see no difference at 2.4 GHz compared to an Intel chipset. On 5 GHz we do see significant differences. On 160 MHz, the 1550 in the Faraday Cage achieves much higher speeds than outside, but that is of little use in practice. The real added value of the 1550 lies on 5 GHz with 80 MHz wide channels. Whereas the 7260 only manages to achieve its full potential when placed in the cage, the Killer 1550 also realizes this with these settings in the real world. This makes this chip seem to deal with a disturbing environment much better. As far as we're concerned, that's more than worth the money.