Guitar->Wah->Powerball->GSP1101 in the loop.
The GSP1101 can do 4CM which is like:
Guitar->GSP1101->Powerball Pre->GSP1101->Powerball FX return/Poweramp
But I found it too noisy. I used the nosie gate on the Powerball itself. But the GSP1101 works great also.
In the loop, I bypass all the models and just run reverb, delay, chorus, harmonizing, special FX, etc.
I LOVE rack systems, but the problem is the extra bulk and you need a MIDI setup to switch them. But they are a bit cheaper if you were to buy pedals for all that they do, and you don't have to tap dance.