Last I checked, DiabloMiner had bugs in its rollntime implementation, and Diablo-D3 stubbornly denied they existed (thus refusing to fix them), so I blacklisted it from using it. Specifically, with rollntime enabled, DiabloMiner is somehow confusing its work and when it expires, and sending shares against work older than 2 minutes, even after it has received new work. If Diablo-D3 has fixed this, and someone is willing to do some real-time testing to confirm it (on IRC), I'd be glad to remove it from the blacklist...