Apologies, but I fail to see how having the same units affects your strategy.
I'm sorry, I suppose I should elaborate.
When you don't play as just line infantry, different factions can change the game for you. Russian Partizans and Cossacks, British rockets, Austrian Grenzers, the naval troops (If you can disregard the war cries). There's a whole host of things you can do beyond 'charge, shoot, stab, die' over and over.
However, are you saying that if you were thrown into any of those classes, you would do the same thing you would as line infantry? Because it'd be suicide, you know.
They could add Foreign units rather then another faction.
I do know that there Prussian Mercenaries were in the war (cannot remember what side, but probably both)
I have never read anything about foreign mercenaries in the war. If you've found something about it, I'll be shocked.
Also, to the earlier comment about Florida drivers;
I resent that, it's the tourists and the people of the peninsula that can't drive. And we all know the latter group is mostly made up of long-term tourists.