Only have a couple hundred miles so far, but shifting with this derailleur seems very precise. No issues with chain slap or looseness with an 11 speed SRAM chain.

Using the cassette on my new indoor trainer with my mountain bike. Working perfectly, smooth shifts, no skipping.

When one of my rotors was fouled with hydraulic fluid I upgraded both to Ultegra. They work very well and the center lock design makes them very easy to install with just a cassette tool and chain whip.

Replaced OEM Tekro calipers and much prefer the braking action, feel and looks. Install was straightforward, they do fit Conti GP 4 Season 28's. take your time adjusting them, and you will be rewarded with a firm, responsive feel and great stopping power.

The Ultegra is the 105 caliper with a stiffening frame added, not sure there's much difference, but given the minor costweight delta, the Ultegra seems worth it. And they look good.