I dunno, I think they're pretty much fine as they are.
If I had to ask one thing, it would be to give dair its Melee hitboxes back, with the very weak reverse one that sends opponents behind the climbers. In Melee, d-throw -> SH dair was a very reliable chaingrab, but in PM it just seems to send people straight up and away. And the d-throw -> reverse dair chaingrab on Captain Falcon and Ganondorf no longer works. It seems like the hitboxes have been homogenized so the entire hammer is just one big fairly weak hit with very low knockback scaling, but I'm not familiar with the actual numbers in how it was changed from Melee to Project M (
Hylian
?). I think maybe the different hitboxes of Melee's dair would give us a little more mixup flexibility out of a grab, which would be nice, since opponents who know DI tend to gut our chaingrabs.
That said, I think the change is far from necessary. The Icies are pretty much done in my eyes. I can't think of any glaring flaws in their design now that the infinites and turnaround walk momentum glitch are fixed.