Or, if you're worried about having to respec, just put the points in PIE. It helps them both and you don't have to respec. Maybe it won't help as much with damage, but you'd need to watch your MP usage less :3 Which in itself will help with damage (or healing, for scholars).
To be honest, I'm sort of thinking that was SE's idea with it. Since you have BLM with int and WHM with mind.... that leaves piety as the only stat not used. (Dex = BRD/NIN, Str = DRG/MNK, Vit = PLD/WAR)
Especially as Piety is what at least Scholars bring with them in form of party bonus (never looked at Summoner, so I don't know if they give Pie or Int).