You realize the 270x is faster than the gtx 570?
http://gpuboss.com/gpus/Radeon-R9-270X-vs-GeForce-GTX-570
Let the man go for the single card he wants to go with.
Yes drivers and everything for crossfire have improved immensely, but, if you are running the same fps on 2 cards as you are on one, the gaming experience is better on the single card no matter who you talk to. Frametime variance suffers from dual card solutions, and even that varies heavily between gaming setups of the same configuration.
Yes, price/performance, the crossfire is best, but has budgeted for higher, and so can get better performance from an single 270x..
As far as the two 270x cards that were linked, the gigabyte is a freiking amazing deal, but is not as good as the asus one.
BOTH are much better than the reference cooler, so you would not be disappointed by going with the gigabyte one