RSharpy ..... glad you impressed with the Zx5-SP.
The reason the car feels better than the D4 (and all it's look-e-likes) is the more forward weight distribution ..... that is why going to the BJ4WE style layout would be a mistake for people who like the current cars characteristics. After all there are enough versions of the BJ4WE/D4/B44 layout out there to keep the people who like it happy and to mean that another copy is unlikeyl to bring anything new to the party and thus would probably not jump off the shelves!
As for the saddle pack layout you not wrong that it CAN be better than the side saddle layout but it requires a fair bit of thought ..... and almost certainyl won't have the cells in 2 x 3 side by side if they are trying to achieve perfect side to side and fore / aft balance (corner weights) ..... if that is what your looking for ... watch this space
