Documentum offers a wealth of tools and functionality for scanning, indexing, and validating paper. The huge difference between Documentum and OnBase is that the OnBase user interfaces are integrated into the scan/index modules. You don't have to index in one UI, then switch to another for further processing like you do with Captiva products. EMC bought Captiva but did not fully integrate it.
The concept of a interoperable modules was probably not considered as the most important aspect of the acquisition. However, as these software acquisitions play out over time, you can see the long term negative effects of not integrating the products. I believe the days of buying software to gain market share only are gone. It may be profitable in the short run, but these purchases need to be well integrated in the long run to be viable.
Let's say you use Input Accel to scan and index invoices for example. You will have to have an approval workflow and an auditing workflow. Which UI is used for the approval workflow, Input Accel or Webtop or xCP, or D2? Which systems tries to match the POs by invoice number, receipts, and total amount, or is this custom? I have seen some of the xCP solutions for this activity and they are complex and expensive and custom to the general ledger integrations.
Scanning and Indexes are configured and executed through OnBase's Clients. There's no patch work of double checking and exporting, there's just one interface called "Import > Scan/Index", that's it. You set up the scanner, give the workstation rights to scan, configure the document type and scanning queues, and you're good to go. Oh, and the workflow can be configured to execute after you commit the batch. It's all in one and takes about a 5th of the time to configure. It scales as well.
Let's face it, EMC treats Documentum as a repository for dumping content. It cares about amassing storage first, then figuring out what to do with it, eventually...