Not sure on the performance hit, you would have to check for some benchmarks, those could be hard to find since most tests are run with 2 sticks of ram in dual channel mode.
As for make of ram, I don't really think it matters, kingston, corsair, usually use elphida or whatever other chips are available (micron, etc.) just look at the warranty, then the reviews, and price.
And remember to check for 1866 MHz memory also.
edithttp://www.newegg.com/Product/Product.a ... 6820231560
also you may want to grab it now, that specific kit has gone up about 10 bucks in the past week or 2 as ram prices are on the rise!!
I have used, kingston, mushkin, g.skill, etc.