What are you guys doing to your rims to wear them out in only 20 kmiles? I can see such limited mileage if using rim brakes in bad conditions, but not when using disks. I wouldn't recommend going over 36 spokes for a single bike (I do have 48 in the rear wheel of our tandem). That number should be more than adequate and going with more would make finding replacement parts harder. Given your track record with the Dyads I'd also consider switching to a different rim. When I've switched rims I look up the ERD in tables like those in the Spocalc spreadsheet and try to find another one that's close to the same so I can reuse the spokes.