Noting the DevonThink website promotes using Avision or Fujitsu scanners with their product, are there any success stories regarding the use of other scanners/MFCs? I’m scoping the program to buy and wondered what other scanners are being used out there with this product… 
I use an Epson Perfection 4490 Photo that works fine with ExactScan and DTPO. As you can guess, I don’t do a lot of bulk scanning. 
With a bit of forum searching you can find lots of topics discussing DTPO usage with different scanners.
The ScanSnap and Avision scanners are speed demons compared to most flatbed scanners, but are not suitable for bound copy such as books or journals.
Most if not all current Canon scanners (and many older models) work with ExactScan Capture. Many Epson models do. Some HP models will work with ExactScan Capture or Image Capture modes of DTPO2. No Brothers scanners are currently compatible with ExactScan Capture.
However, some scanner models that are not compatible with the built-in ExactScan Capture or Image Capture scanner control modes in DTPO2 come with the manufacturer’s scanning application that can send scanner output to DTPO2 (as does ScanSnap, for example).
Make sure that the scanner can be operated by your Mac, or by its own controls. Worst case, any scanner compatible with Mac OS X can save image-only PDFs to disk, and those PDFs can be imported into DTPO2 using the command ‘File > Import > Images (with OCR)’.