I happen to think taken down enemy cav is a huge bonus to the rest of the team. Having cav superiority can change a losing round into a winning one.
I agree. I would probably not go 1 vs. 1 though, maybe if I was a tad bored, or if it was possible to ambush one with a couch around a house corner. If the other cav was engaging enemy cav, I would of course help out. 2 cav vs. 1 cav should secure that one couch the horse/rider, which would help your team a lot. I've always aimed for cav when being crossbowman and archer too, because I believe they're the class that really can turn a game on its head.
Btw this is all as a lancer cav, what is your horse char Gurnni? 1h cav were much more badly hit by hit, practically unplayable from what I heard.
I have both at a decent level (24 and 26 I think), but I only played lancer yesterday. I have no idea how the 1H cav had it when the nerf first was introduced, but I don't doubt it. 1H cav relies more on good maneuver and stop - start playing than lancers.