I've been playing a lot of vanilla 1.5 as part of testing the EB buildings for the port. I wouldn't be in too much of a hurry to tinker with the formations in the 1.5 version as the patched vanilla battle ai, formations and *especially* army composition is much improved. Or it might all be due to the much better army composition. Hard to say.

Either way some of the stuff people have done to mod the formations files will be based on work-arounds for the weaknesses of the earlier vanilla game which might not work the same way with better ai armies.

(Plus the EB formations work very well imo.)