The Sony DRU-510A is supported in the latest version of our products. We have this drive here in the lab and it is working quite well.
Unfortunately we are not able to provide support for the Dreamcast format. This is not only due to company policy, but limitations in our means to provide support for this seemingly difficult format for many writing drives to handle. I haven't spent any time with any of these image files that our customers are experiencing trouble writing to disc so I cannot comment as to why some drives seem to have difficulty writing this format.
Do you still have this Plextor drive in the system? If so, please try writing with the same version of DiscJuggler and this Plextor drive. Are the results any different?
You can contact us directly at firstname.lastname@example.org if you wish.