Fair enough, yes I haden't thought of that. We tend to play BIG multiplayer games e.g. 6-10K a side and sometimes bigger.
As to the number of cavalry being taken, it completely depends on the army type, the player and his collection.
Looking at one of my old, used army lists; If I was fielding 4K of my O+G army, I would probably field 12 units of Boar Boys, 6 units Goblin Chariots and 6 Wolf Riders.
My friend fielding his 4K Brettonian list would have a total of 20 units of Knights/Grail Knights (ouch). It seems harsh to him to say sorry mate, you can't field all those units you spent hours painting up?
I guess there will never be consensus so we'll just have to have group based house rules.
Dave