I don't know about AFE dry vs K&N oiled (although they claim their oiled performs better than their dry), but I always found this old graph AEM used to post very interesting.
Basically it shows that K&N filters flow the best unitl they are litterally caked with dirt (where it drops off is like a measuring cup of dirt!), afterwhich the AEM dryflow performs better.
I don't think AEM has this on their site anymore... still, it shows that K&N is a pretty good filter (best clean flow of the lot!)
Hmm... Actually, the AFE pro dry (and one other -- is that the oiled one?) is on there... neither of them doing too well either...
Again, these results are from AEM, and considering their filter isn't even shown to offer the best flow when clean (which is probably why they pulled it -- bad adverstising!), my guess is that it's reasonably reliable and objective info to use in deciding on an airfilter.