I was thinking about how to protect very big buildings and cities. Indeed, a 65*65*65 square force field would be too small, especially for some SMP constructions/cities, so to have the possibility too combine several shields would be very great.
For example the freq trans might have the hability to change the frequency of field generators. The force fields produced by field generators with the same frequency could then combine into a bigger one without weak area between them or without the need to carry 4 or more Freqtrans (forgetting which freqtrans is for what force field).
Considering energy this system would make one big shield more rentable than several little ones due to the cost of the shield generator itself. Because if you are able to power several small shields you are able too power a big one of the same surface.
But a good point of it would be the optimization of the protected surface due to the shape created by the position of field generators.
Also the texture of the shield could be better : for example a succession of coloured (transparent orange or light blue) panels with an extending brighter color when touched in an area.