I have gotten a response from our specialist with a LOT more detail. I'm not sure this answers your questions, but it does provide the problem:
"We struggle with a couple of issues with the DocuSP RIP on the iGen. I won’t go into elaborate technical detail, but the outdated RIP forces us to use cumbersome workflows that cause significant production bottlenecks. In essence, it was designed for 20th-century workflows and file formats, and is unable to handle modern files without extra labor and time-consuming processing.
Specifically, the DocuSP technology does not support Adobe’s PDF Print Engine architecture, which processes native PDF files without flattening into the outdated PostScript file format. In our current workflow, we save files as PDF files from InDesign or other programs, then the iGen operator opens the PDF files in Acrobat and selects Print to send them to the DocuSP RIP in PostScript format. Acrobat’s Flattener engine analyzes each page during that process, converting any transparent elements to raster format due to the inability of PostScript to handle non-opaque elements. That step can be extremely time-consuming with files containing many large images and/or transparent elements, and it can produce very noticeable distortion and discoloration in transparent regions. Once the file is converted to PostScript, it then has to spool over to the DocuSP print queue, a process that can take as long as the previous step. It is not uncommon for complex files to take 3 hours or longer to successfully transfer to the print queue. The iGen operators often have to release complex projects at the end of the workday, and sometimes the files are still processing in the morning when we return.
In addition to the time it takes to transfer jobs to the print queue, we have to spend much time preparing files to minimize the possibility of transparency rendering errors. Most of the EPP operators are accustomed to the Prinergy EVO system we use to send jobs for offset plates–because Prinergy supports the PDF Print Engine workflow, the operators don’t need to worry about scanning for transparent regions and layering/preflattening to avoid rendering problems. It can take two or three times longer to prepare a job for the iGen if it contains complex transparencies. Despite the time and effort we extend to catch those problems, it is common that the operators discover flattening problems once the job is printed, so they have to bring it back to EPP for rework. Then we have to repeat the whole process over again."
