Yeah, the difficulty isn't bad for Langrisser IV. The worst thing I remember was facing any enemy with a bunch of Nixies, which seemed grossly overpowered. Sea terrain bonus, decent speed, and a strong ranged attack just wasn't fun at all. It could just be that I was terrible at the game back then, since it's been a while. From what I've heard about the Playstation version of IV though, I pity anybody playing it instead of the Saturn original. I read that the soundtrack took a hit and apparently forcing V's battle system into IV without any changes broke more things than it should have. Haven't tried the Playstation version to confirm it, but it sounds nasty. Would be worth picking up the Playstation version of V one day though, since that one has a (much needed?) Hard mode. Maybe on Hard mode there will be an actual reason to use a character not named Sigma. :P
Anyway, about IV, I've always been a big fan of Listell. She's an added bonus since by default Chaos routes are my favorite and the C route isn't that bad either. It's a little disappointing how short the B route is, but I love the option to say "screw you" to all your goody-goody friends. Actually, I think that's one of the things I really like about Der Langrisser and IV. Being able to turn on your Light path friends is good, because when you really think about what they are doing, they don't seem like the good guys anymore. (This is why the Independent path for Der Langrisser is great. Rejecting both sides' claims about "the other side is pure evil" is a good thing. I'm biased though, because I'm a sucker for "how could you" responses.)
Also, no Langrisser topic would be complete without mentioning how bad III is. Don't play it unless you're masochistic. :(