The 25-06 is an AWESOME round. Same trajectory as the 7mm Mag, w/o all the fuss. It will take even big deer, etc. out to as far as you need, and I can't tell the difference in kick between it and a .243. I am biased
, as it's one of my favorites.....it will push heavier bullets faster than the .243, and is in the legitimate realm of the .270, .280, 7mm-08, etc. I put the .243 in the class with the .22-250, .220 Swift, .250 savage, etc. Nothing against them, cuz they do what they do very well...but the .25-06 is in the next power band, IMO......either way, for the type of hunting you are talking about, both calibers will work just fine. Get the one that tickles your fancy and shoot it a bunch.
Here's a thought: Let the ducks work and decoy.