I find most battles are decided on who routs first, rather than simple killing ability (though obviously the two are intimately connected!), and therefore would be interested to know what effect unit depth had on morale - ie, would a thin, two rank phalanx be more likely to rout than a deep one?

If the computer calculates the morale of each soldier depending on how many allies they are in contact with, whether the whole unit is contiguous etc, it could have a major effect - in a two rank formation each soldier can only be in contact with a maximum of 5 allies, any greater depth and all troops except the front and back rank could potentially be in contact with 8. Also, a cavalry charge may be repelled by a two rank phalanx, but even so, the charge may make temporary gaps in the formation, even if they only last for a few seconds, it cold effectively split the unit into two or more seperate bodies of men - I'd guess this might make routing more likely?