I have the same combination on my one remaining derailleur bike. I re-used the 16-20" SON hub when I sold my Moulton TSR, my LBS had Mavic Open Pro rims in 28H in stock at a reasonable price, and I built the wheel with 2mm plain guage spokes.
The SON hub powers an Edelux front lamp with a B&M Secula rear lamp on the mudguard. The combination works very well.
For riders interested in speed/performance, drag should be slightly less than with a standard dynohub, the light starts at slightly higher speeds, for me the latter isn't an issue on an unloaded lightweight bike.
