Dutch player looking to switch to Kings Indian defense or Grunfeld?
Well, certainly the Grunfeld has nothing in common with the Dutch and it is very difficult to keep up with all the theory, hence the KID is the easy answer.
Also consider the Stonewall Dutch (although it's bad against 1.c4 and 1.Nf3, but instead you can play the Hedgehog via 1...e6 against these moves as I can see you play the French).

Staunton is harmless, both ...c6 and ...Nc6 systems seem good for Black. I played the Dutch (...e6 variety) for half a year, and it was all fun, until people started playing 1.d4 f5 2.Nc3 Nf6 3.Bg5.
King's Indian is much closer to Duch than Grunfeld, but a lot can be said for all the funny systems with ...g6 and ...d6 but without early ...Nf6.

You might try starting with e6 and saving f5 for move 2 if you don't mind playing the French defense.