Given a choice between keeping a Model 65 with a 3 inch barrel or trading for a Model 686 with a 2 1/2 inch barrel, I would, without hesitation, keep the Model 65.
Your Model 65 has a number of advantages over the 686 when it comes to being a carry gun. It has a smaller frame and cylinder, which makes concealment slightly easier. It has a full length ejector rod, which makes ejection of spent cases more consistent. It has fixed sights, so they will not snag on clothing, dig into you, and are less likely to be damaged.
The advantage of the 686 would be ammo selection. It can handle a steady diet of full power magnum loads better than the K frame. That is its only advantage over the K frame.