The discussion that has originated in the thread seems really interesting.

In my opinion the most important statements till now are the subsequents:
1) the 4tpy system risk to be unhistorical in the fact that allows the creation of enormous conquests in very limited periods of time (25-40 years, whereas, in reality, the achievements of a strategic and tactical genius like Alexander the Great remains absolutely unique),
2) the 2tpy system isn’t realistic so far as involved in the tactical level, because it restrains so much the army’s and navy’s movements,
3) the great amount of cash granted by the inner script unbalances a bit the game, allowing the AI controlled factions to field vast armies,
4) the presence of great stacks of mercenary troops isn’t historical.

Maybe the right solution could be this one:
• 4tpy system wich solve the problem n. 2)
• heigthened period for training units, 2 and maybe also 3 turns for infantry and 3 or 4 turns for cavalry, chariots and elephants: this would be historical because the troops needed at least six months to train a bit and would slow down not only the process of building up vast armies but also the expansion rate of the biggest factions solving problems n. 1) and 3),
• balancing minimod to solve problem n. 4).

Any comment?