I sometimes temporarily replace gear that may conflict with what I want on another piece of gear. Epic Affixes don't seem to care, but Ruby and Obsidian Affixes tend to look around at what you already have available.
And yeah, I concure with Mr Scooty. Choose your drops wisely, and configure from there. I'll sometimes dump all but one or two Affixes on a drop, and reconfigure the rest just to get a set of gear that works well for me.
If you can't find what you are looking for in a drop from your own class. You might try converting a drop from one of the other classes. Below is an incomplete list of conversions. I'm still working on testing the rest.
Wizard. Warrior. Rogue.
Gauntlet. Axe Bow
Sword. Sword Dagger
Wand. Lance. Pistols
Orb. Shield. Smokebomb
Like I said the list of conversions as I know of them is incomplete. There might be a more complete list in wiki. Not 100% sure of my own list without further testing.