The Klein Performance is an unusual frame, it has rack mounts, long chainstays, is very stiff and has very steep headtube and seattube angles.

It can be ridden like a race bike, you can more-closely draft a lead rider due to the steep headtube angle, but a following rider might touch your rear tire.

The weight distribution puts a lot of weight on the front tire, which calms the steering but might cause you to lose rear wheel traction on a steep, wet surface.

The chainline is forgiving, again due to the long chainstays.

Overall it's a pretty good bike. Tire clearance on the models having the tubular Henry James fork crown isn't great though, and rear axle spacing is fixed at 126mm.
I liked it enough to upgrade to 10s, putting a 10s 12-30t Shimano cassette on the un-modified 7s Ultegra freehub.
The ride quality does not seem harsh with 25mm tires.