I haven't played 3rd edition yet, but I played 1st and 2nd editions extensively. I always removed the odd/even limitation on using 1 move segment for maneuver. so basically 1 move segment can always be used as a maneuver segment. you can limit it a bit more based on scenario or even based on hte army used as you see fit. i wouldn't use that particular house rule for anything prior to the Napoleonic era though.
the combat is a bit random. statistically speaking, higher die types have and advantage, but it's not as big as people perceive it to be. If the higher die rolls terribly, you can get some real upsets. that's actually one of the things I like about the rules. Guard units aren't impossible to fight in a system like that, so putting them on the table is less of an issue. In campaigns or linked scenarios, it makes people be more careful with really good units because they aren't invincible.
I personally never like the opposed die role for shooting. I know that the combat system is sort of a combination between combat and morale, but i just always thought it felt wrong. I toyed with using a target number instead of a defensive die rating. so D4 is a 2, D6 is a 3, D8 is a 4, D10 is a 5. it makes shooting a bit less deadly and gives a bigger potential advantage to higher die types.
one of the things i like most about Field of battle is the asymetrical turn sequence. It's exceedingly hard to "game" the system based on turn sequence. Everyone i know, even people who didn't like the system, admitted that they found themselves thinking less about the rules and more about how to achieve objectives in terms of tactics, which I think is a really great bonus to the rules.
Also, it may not apply to you, but the game plays very fast in multiplayer settings as well. With 1st edition we did a big Waterloo game on a 24x6 foot table with 2500 28mm miniatures. it was played to conclusion is about 6 hours with 21 players.