I'd stick with the 10600, since that's what all the other DIMMs will be.

Working with large images in Photoshop, faster RAM will improve performance (slightly, just as it improves game performance slightly), but you'd have to have it all the faster speed. I'd not bother (even though I did bother when upgrading my system from 16 to 32 gig, I replace all the RAM with faster--I had a buyer for the old stuff though).

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs