I've done a little punch n pie, but I really just stole the idea from Tiji of DA (or more recently, Arky of HH). Basically, people mistake your sword for a blue and you surprise them with your range. Then, once they figured out your "gimmick" they get sloppy and think they can just rush you. When they do that, you can
A) drop the shield and red them
B) shield kick them and either red or wrap
C) just keep fighting like you have a long blue
Punch n pie on a bridge is nice because you have a long range, while also being able to block arrows/javs/spears that would usually pose a greater threat to a simple red-wielder. However, when it's time to do work, you can drop the shield (or if you have it rigged, sling it on your back) and surprise people with some devastating red hacks. Repeat as necessary.
In the open field, you can play around with it alot. It's alot of fun when you're working with a squad because you have enormous reach with the added psycological benefit of your opponent knowing that any moment you could switch to red mode.