I've owned Colnagos since 1995 and had a couple of Z1s from 2007 to last year. Both are excellent bikes with the Parlee probably riding a little more smoothly than recent Colnagos (my newest is an EPS). The Parlee was also quite a bit lighter than even recent Colnagos.
The big difference is in geometry. One Z was stock, the other custom based on geometry of my former LBS' house brand Italian frame. I just found Colnagos more stable at speed and preferred their handling to the stock Parlee. After a big crash in 2010 (18 days in hospital in Italy), I've been more nervous and just didn't find the Parlees working for me. I couldn't ride the stock one comfortably at all while the custom had an Alpha Q GS10 fork that was too light for me. If I could have easily switched the fork for one with the same geometry, I might have kept that custom Z but have now sold them both and put the groups on NOS C40s.
As LionelB says, you could do the Parlee in any geometry you choose. If you like something in particular, that might be the way to go.
You think longer trail would have helped the Z1 to be more stable at speed?