Due to some folks having an issue with the size of the original mod, Imeo's making the production AVS with a collection tank 12 mm smaller; that's why I'm calling mine the 'Grande'. Besides making it match the circumference of the GGTS, another reason for the size is to make the juice tank as large as possible. This way, a normal vaper can fill the tank in the morning and not have to worry about juice for the rest of the day.
It's possible to make the ggts a lot smaller, especially if you vape at 3.7v. You can put in a single 3.7v cr123 (naturally, I prefer imr or high drain batteries) and screw the afs onto the top of the telescoping piece. (See enclosed picture.) Again, the production version will be 12mm shorter.
It's really all a matter of personal preference. I'm normally more concerned with having to carry extra juice or batteries than the actual size of the mod (one of the few benefits of having to wear a suit and tie to work). But to be honest, I could see the benefit of the mini configuration; I can stick this in a shirt pocket and throw a couple of cr123's in a pants pocket very comfortably.
Finally, if size is your primary consideration rather than versatility or capacity, one of imeo's next projects should be the AFS for the slim and super slim. Even though his flagship ggts got its own AFS first, I'm sure imeo will think of another few innovations or improvements by the time he gets around to designing and building that mod.