A single breather has worked great for me. It is a -12 line running from the top/front of one valve cover to the puke tank pictured.
You will get a little condensation in the puke tank (depending on engine operating temp) mixed with a small amount of oil from vapor. But no mess out of the breather as long as your engine is (rings) sealing fairly well.
http://www.imagestation.com/picture/...7/e77eaf66.jpg
This is with 598ci and 950hp.
The tank is a Jegs brand, and it is a pretty nice piece for $70 (includes breather, jic to an fitting and jic plug.
Warp Speed