I'm waiting on another RR1.1 to replace the old DA16 I killed on my brevet bike, and I'm currently running an RR1.1 on a SON28 laced 32h 3x with Champion 2.0 spokes up front and an Open Pro 32h 3x laced with 14/15db spokes to an Ultegra in the rear.
They're both nice rims, but I prefer the DT RR1.1 single. It's lighter (just by a little bit, and I'm not a weight weenie, but on a distance bike certain things like rotational weight do help). It's slightly deeper section gives it a tiny bit more rigidity. But most of all, it's quieter! I don't know what the difference in materials/design is, but damn the Open Pro is a freakin' noisy wheel! Chip-sealed roads make the thing sound like it's about to vibrate apart. It's like the rim is an amplifier for road noise.
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"I feel like my world was classier before I found cyclocross."
- Mandi M.