Whoo boy...I already have about two and a half pages of notes!
 
Okay.
 
Well, first off I will say that as far as I can tell, the sonic changes are due to the pads.  I've A-Bed back and forth between each can with their stock pads, A-Bed back and forth with each can wearing the latters pads, and A-Bed back and forth with the same can switching pads.  It's a little hard to due the last one, as I have to pause and unlock all the bayonet locks then swap pads and relock them (usually having to reposition that little grey foam that likes to fall out).  But, again from what I've heard so far the Q701 with 65 pads sounds like the 65 and vice a versa. 
 
So the good news is I think you can mod any x70x into anniversaries by using their pads.  You can also "own" both types of sounds if you own both pairs of pads.  No need to keep two headphone around..
 
The bad news is, I don't know which can I like more!  They both do some things well. 
 
As was ruled out earlier in the thread, the changes aren't just limited to bass, nor are they just limited to bass mids and treble.  I also detect some soundstage changes as well.
 
This is where the Q701 still appears to have an advantage.  It's main strong points are the soundstage size, sound separation, and air.  The K702 65s strong points are the thicker bass (obviously), as well as the rest of the balance being a bit thicker and weightier, more "musical" as head-fi would call it. It's a little warmer and a little darker.  BUT, the soundstage sounds a bit more intimate and upfront, whereas the Q701 still sounds more laid back and spacious.
 
My first thoughts after hearing the soundstage were, "OK, so the bass isn't "free."  Those flatter non-angled pads are compressing the soundstage."  I'm not 100% positive though, because I heard the anniversaries throw a couple sounds out pretty far, at a similar distance as the Q701.  So now I'm running some more tests to try and further disect the soundstage differences to see how much of the soundstage differences come from a byproduct of the weightier sound, and how much of it comes from actual having flatter pads and what role they are playing. 
 
I don't want to conflate a weightier sound with a smaller soundstage, because that's the impression you get at first listen (similar to how some people say the Q701 soundstage is smaller than older x70x).  Possibly the soundstage sizes are similar, but the 65s have more sound trying to fill up the same space (soundstage size) or even slightly smaller, which means you can't have as clear separation as some sounds start to bump into each other.
 
Or possibly the flatter pads are indeed a bit detrimental to the soundstage, and pan the sounds harder to the sides and decrease the depth.  Still working on analyzing that.  The flattest part of the Q701 pad is just about the same size as the entire anniversary pad.
 
I also think the anniversary sounds more like a modded Q701 then a universally "improved" Q701.  And judging by the pad swapping I did, it may in fact be primarily a pad "mod".  I wouldn't expect a pad mod to completely improve a headphone without some side effects though.
 
I think it's safe to say that the anniversary's balance is more general-purpose, where usually the x70x gets recommend more for specific genres (usually instrumental stuff) then others.  If your someone who digs the x70x but listens more outside of it's usual recommended genres, then the anniversary may be a better choice.  If you mainly listen to the "typical" x70x genres though, the original x70x might be better as that extra air and soundstage separation (and size?) is pretty important to those genres.
 
Still working on it...
 
Also, the anniversaries are quite sexy looking.
 
BTW, my initial impressions share some similarities to Blackmore's here >
http://www.head-fi.org/t/626971/akg-k702-65th-anniversary-edition/1515#post_9193460
 
Also this quote from Preproman from the previous page is pretty accurate "Q701 = extended treble but not harsh clear crisp balanced with more air.  65th.  Treble rolled off a tab bit but not in a bad way. More bass presence and the mids are more lush.  Still very balanced with less air"
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....I've already listened enough to "normalize" a little to the anniversaries then gone back to the Qs and thought they sounded more "audio-technica-y"
 
That's probably the experience you will get when tdocks Q701 arrive.  They will sound thinner, lighter, and brighter (similar to old x70x).  You probably won't like it after normalizing the anniversary sound.  But, the soundstage and imaging are worth paying attention to (and the air is appreciated as well).  Those are BIG for me.
 
I think they're both balanced in their own way, and are like variations on a similar balance.  Whichever one you've been listening to more may sound more balanced to you. 
 
So far if I could combine the two, I'd keep the majority of the anniversaries balance, but with the upper air of the Q701 and it's spacier sounding soundstage.