Exactly, that is why I'm a little confused. Running a full size lipo pack is already on the lighter side, so putting a short pack in seems kind of odd. But, there are at least 3 AE drivers testing this. They don't say anything about adding weight to compensate for the short pack. They are just mentioning the weight that is normally added to a modern B4.1 +8mm car.

Yokomo's new 2wd, offers this configuration as well, but none of the cars in the press photos show the electronics on the center line. They simply show one car with a standard size pack and one with a short pack with the electronics in the traditional locations. The only benefit they mention, is greater tunability. So again, you have more weight distribution options, but the car is still over 100g lighter in general.

My hypothesis on the whole matter comes down to the latest trend in 2wd. The longer chassis design. TLR, Associated, Durango, and now Yokomo all subscribe to the longer chassis design concept. Coincidentally, at the same time, short battery packs are being tested in all of these cars. Short battery packs were none existent until longer chassis began to pick up steam, for example the TLR 22. This makes me think that when running a longer car, a shorter battery pack may be more ideal, because of the way the chassis reacts to that particular amount of weight. A sweet bi-product of this, is that the driver has more options for weight distribution.

I don't know, I could be totally wrong about this. It just seems odd to me that 4 company's(that we know of) within the last 10 months have not only started using longer chassis, but shorter battery packs to go with them without any weight compensation.

I am not an engineer, I am just speculating. That is all.