One thing to be aware of when using separate balls of yarn to knit all the way across is that things can become a knotty mess if you're not paying attention. I put each ball in a separate container and then made sure the ball I was getting ready to use was on the correct side (i.e., first in line and not twisted around any other strands). That was a bit of a pain, but really, it wasn't too much trouble once you get used to rearranging containers every time you flip your work around.
You also have to pay particular attention to shaping and be sure you know which side is the sleeve side and which side is the neckline side. You most likely won't have trouble with that since your button bands will be in a different color.