I had some climbing and descending, the bike handles fine, no drama from the very short trail, and no shimmy at any speed up to 35. I took my hands off the bars for a moment at 30 MPH, no problem. Overall a very pleasant and comfortable ride.
I swapped out the 32 mm Rando Hypers for 28 mm Rubino Pros, and the ride is still quite plush. Those long fork blades seem to really soak up uneven pavement.
For those curious, the frame weighs 4 lb 3 oz, and the fork is at 1 lb 13 oz after cutting down the steerer. Back in the day a 6 pound frame and fork was a pretty typical racing frame, so I think it's an entirely reasonable weight for a sportif made from pretty traditional tubing.