Yep, I think playing other games does improve your skills.
You just have to be careful that you don't end up dabbling in all games and never really getting good at any of them (he said, casting a critical eye over his own, somewhat shambolic poker career).
PLO will teach you the importance of position. It will also give your mental game a solid check-up, too.
Limit holdem will have you value betting like a demon.
Good Luck.