I think for the most part Cav is fine. The only instance I think they kinda blow is that they are too easy for a single human controlled footsoldier to crush. A player controlled line infantryman with nothing but his bayonet can shutdown a decent sized cav charge. I noticed this first as playing infantry, and then when I started to use cav it became even more apparent. I don't think cav needs a buff, but I think something needs to be done to make it not that easy for one guy with a bayonet to shut down a charge. Now of course, a cohesive line of 2 or more ranks who are prepared is one thing. I'm just talking that, even with heavy cav, 1 cav vs 1 guy with a bayonet who isn't a complete tard, he's (the infantryman) going to win, even in a head on, full speed rush.
Of course this is all anecdotal but I'm sure others have seen/experienced this.
If you are charging cav head first into a line of muskets in this era, you are doing it wrong. The musket killed offensive tank cav. You have to be quick and sneaky and surprise the enemy.
Good point and it's the rule that is proving the exception. Like I said a cohesive line who is prepared would be stupid for cav to rush in to. Just as ridiculous as how 1 lineman with a bayonet can completely own a heavy cav charging at him, even from an angle or a flank.