At lower levels (below lvl 150), you're only really going to want this at the very minimum that you can have it so that mobs don't get critical hits on you very often.

You'll be able to find this out easily ;) If you find that you are getting critted a lot, raise evades a LOT next level. Consider even putting 100% of the levels IP into Evade-Clsc or Dodge-Rng (whichever is lacking, if not both).

At higher levels, you'll want to have them maxed for sure.

As for Duck-Exp, there is less and less of a need for it as time goes on. I'd still recommend maxing it at high levels, but I wouldn't worry about it for a while.