The one Colnago I owned died a quick death on the rear end of a flatbed truck that magically appeared at the exit of turn 3. Up to that point it had done pretty much what it was supposed to. No real complaints or praise. It was a bike -- which is about all that I can say for any of the Colnagos I have ridden.
That's also about all I can say about Masis. If pressed, I'd tell you I prefer Masis; I think the handling iss a bit more neutral. Never felt the urge to break into song on one though.
I had a few Serottas that were all well above average. I agree that the front ends were a bit faster than average, but never twitchy, and fine for a crit bike.
Never owned a Sachs (that will change) but the ones I have ridden have been exceptional. Very stable, but still very "connected". I like a bike that does what you want, when you want it to, and nothing else.
The finest frame I ever rode was built by Della Santa. I measured it up and wrote it down, but didn't find anything magical in the numbers. Whatever it was, that bike was utterly stable, perfectly neutral, yet seemingly wired directly to my brain. That frame felt like a best friend, and out of all of them, it's the only one I say that about.
I don't begrudge the folks who enjoy their Colnagos, and I can even work up a bit of jealousy for the folks with nice older Masis. But as far as I am concerned they are pretty much just two sides of the same batch (or even mass) produced coin.
That ought to get me yelled at:-)
Noel Hoffmann
Huntington Beach