I would but the Cervelo hands down, I wouldn't even look at the other bike. (That's assuming I was confident it hasn't been crashed or abused.) The way Cervelos handle is exactly the way I think a bike should handle. It's been true of every one I've been on, my current bike is a Cervelo C3, I knew I was going to buy it before I got it out of the parking lot. Turned it once and a smile broke out across my face.
That reason doesn't apply to you or anyone else, so go test ride them both. Longest rides they'll allow you.