I'm just torn about the capstone thing. I'd like to include handy skills and abilities from, say the Monk when playing my twin Wizard (or from Ranger or Rogue for my Twin Druid) but I worry that I will regret it when I reach the equivalent of L20 and want the capstone too.
You can mix and match two classes' skills and forego any Capstone. Or you can put in only a single class's skills and get the Capstone. And you can switch between those two in town fairly easily.