Honestly, I don't know. I've played even less of Disgaea than I did of La Pucelle (even though I did have a handheld Disgaea game, I just never really got into it).

From what I remember of those two titles, La Pucelle seemed to be a little better on the tactical level, encouraging a bit more thought about movement and placement, due to the energy portal manipulation. But it's been a while since I've played it.

You seem to be right, though, as apparently at least one of La Pucelle's bosses showed up in a later Disgaea game.