i commute a ton on my road bike, which has a d-a 7700 rear and a d-a 7800 front. both are amazing hubs. the rear was used, but i've had the 7800 since it was new for about a year now. they hold up great, are INCREDIBLY smooth, and i've found they keep dirt out super well.
i think as long as you stay alert to maintenance issues and aren't afraid to do so, they'll be fine. so many people are the set it and forget it type, so cartridge is the best for them...