I have ran both the K&N 2780s and the Ramair.
I have also had both setups on the dyno with the same bike.
The Ramair breathed more air and required fuel addition, hense more power, but due to atmospheric differences of the dyno run dates, just a little improvement in horsepower was resultant.
I'd say Ramair has a definite edge, but if your engine is stock, the K&N 2780s will work fine.
To me (stock engine + CES) the Ramair felt more snappy and yielded more top end.