Stiffer rims are better, because they allow for a longer stress-affected area which reduces the amount of load change in the spokes. That's how Bontrager's Carbon wheels weigh very little, but have no rider weight limit. Their carbon rims are stiff. I'd use a Bontrager Mustang Offset spoke bed rim in this application with DT Swiss Alpine 2.3-1.8-2.0 spokes and brass nipples, tied and soldered. OSB rims are a must for heavier riders, since you get a nearly dishless wheel that way. I'd even warranty it for the life of the rim against spoke breakage and truing.

DT Swiss had a problem with the elbow design years ago, but this was revised. They're fine now, and their QC smokes Wheelsmith. Sorry, but after a few thousand wheels, it seems like the only ones that regularly come in for warranty work had WS spokes. Many failed at the start of the thread due to too deep a thread being rolled. Never had a DT do that...and you should be using washers anytime there is a sloppy flange to spoke interface, anyway...