thumbs me up for this as i asked this a gazillion times.
the average user does not need 2.6ghz. how do i know? i have the 2.3ghz and it seems just as snappy as my 2.0ghz 2011 15".....as well as the knowledge of countless opinions on that question.
normal use, you will not notice any difference.
unless your kiling your mac with intensive stuff like heay gaming, alot of video rendering, etc, even then a 2.6ghz will make little difference.
however if hving a 2.6 will give u peace of mind, go for it.
i got my retina 2.3 yesterday, and its nice......
PLUS it has a samsung screen so hell i aint risking taking it back LOL