In the last little while I’ve done a couple wheelsets using DT Swiss hubs and rims. Both sets use DT 350 hubs; one rider selected R470db rims while the other chose RR521db rims. If you’re thinking about building a set of wheels yourself, I can testify these rims make the work painless.
Pictured below are two wheelsets built with 650b Pacenti Brevet rims, one built in March and another more recently. I was happy with the steadiness of the rims and would recommend them if they meet your needs. The first set uses Campagnolo hubs; SON and Shimano hubs on the second.
Rear hex drive nipples were designed to handle increased torque but they also prevent builder’s marks on external nipple wrench flats. Some people like rear drive because the turning direction is intuitive — clockwise is tighter. Since the external interface exists just the same, you can forget the rear hex drive if you prefer (or treat it as a backup to save the day if a nipple cracks or rounds off).
The Sapim hex drive is 5.5mm. It’s a balance between making the interface as large as possible while leaving room for tool clearance at the rim holes. Even so a thinwall tool is often necessary. I have three in my toolbox. My main tool is the Park SW-15, a 3-way that fits nicely in the hand and provides good leverage. Blue tape marks the 5.5mm end. The Park Tool SW-18 is a screwdriver design, which reaches into deeper rims and may fit better in race toolboxes. The Sapim factory tool is excellent quality and handles even deeper rims but may be too deep for everyday use.
This is a sweet set of 650b gravel wheels. They’re put together using Onyx rear and SON front hubs paired with Light-Bicycle carbon rims. These wheels are destined for a year-long journey so I’ve selected Sapim Force spokes, which makes builds more bulletproof. For more casual use lighter spokes would definitely work.