BL - the more formations you have, the slower it plays (trust me on this OK
)
Chroma, I see where you are going, but total flexibility won't really work - as I think you already know deep down. Equally, I thought your idea was not so much the individual formations as the variety of upgrades each formation could take.
I think this might be a lot more acceptable if you changed the format declaring the minimum and maximum of each formation and upgrade of the army list:-
Formation   ÂÂ
Units           ÂÂ
Cost      ÂÂ
Upgrades"name"       4-12 Unit name     xxx each   "1-n kkkk", "1-n pppp", "1-n ssss"
.           Transport name    (+xx each)
This way you could alter the minimum size of each formation and its upgrades as appropriate and cap WE etc. So Fire Warriors might be 6-12 with 1-4 Pathfinders, while Crisis might be 4-6 with 1-2 Pathfinders (or what ever takes your fancy).
Alternatively, you could stipulate the minimum and maximum of each formation size including upgrades, so FW might be 6-12, while Crisis might be 4-8 etc, effectively creating a number of upgrade 'slots' per formation.
Either way it certainly will take a lot of effort to generate something even remotely balanced and I have a strong feeling that it would ultimately end up looking very similar to the current 5.1 list.