DT Office 1.5.2.1 does not appear to work with said scanner 
When hitting the Scan button or File -> New Scan menuoption
it just hangs on the “Initializing Scanner” dialog.
Does anyone know of a solution to this problem, which is all
the more annoying in that I actually bought DT Office and
this scanner because I wanted to use the former to OCR
a couple of documents ?!.
Sorry, I don´t have a solution for you. But I have the same problem with a HP Photosmart C4380 here. Seems to be something is realy broken with the scan function of DT Pro Office. Did somebody beta testing? 
We don’t have access to all the scanner models out there. But TWAIN-compatible scanners with a driver compatible with current versions of OS X will likely work. The included ExactScan Capture software supports a wide range of scanners.
Try this with a TWAIN-compatible scanner:
If ExactScan Capture is locked up, click on the Apple icon in the menu bar and choose Force Quit. Select ExactScan Capture in the Force Quit listing and force quit it.
Unplug your scanner. Wait a few seconds, then plug it in again.
In DT Pro Office choose File > Import > Document (from scanner).
If you can successfully scan, please report your scanner make and model. Likewise, if you can’t.
Users of TWAIN-compatible scanners with automatic document feeders are asked to report whether the ADF feature is working. Note that ExacScan Capture provides an option to use the scanner’s own interface, if that’s useful.
Note: These instructions do not apply to Fujitsu ScanSnap scanners, which have their own driver application, nor to other scanners being used with their own driver software application.
A number of Canon scanners are TWAIN-compliant but also have their own driver application, Toolbox X. My CanoScan LIDE 500F will happily send scanned PDFs to DT Pro Office for OCR and storage, using either ExactScan Capture or Toolbox X.
If a scanner does not work for you, please email to support@devon-technologies.com. We will forward this to the ExactCode team and they’ll have a look. But, as Bill said, there are so many scanners out there and TWAIN is a horrible ‘standard’, there will always be issues. However, we support way more models now than we ever did with Image Capture.
[forwarded to DT Support]
This only to restate my point above. Whereas Image
Capture does recognize, my Brother 7010L All-in-one
Laserprinter just will not work with DTPO, no matter
what I do .
Your message has been forwarded to ExactCode.
I just checked the Brother Web page for OS X downloads at http://www.brother.com/E-ftp/macosxstate-us.htm.
It notes that if a product isn’t listed there, it is NOT compatible with OS X 10.5.x. I couldn’t find your all in one listed.
The “Mac OS X 10.5 Support Statement” from Brother
that I’ve seen is at: http://www.brother.com/E-ftp/macosxstate.htm
and my DCP-7010L is on the list of supported
printers, besides as I’ve stated Image Capture works
fine in Leopard.
The lack of support (at the moment) is not a catastrophe
though: I’ve sorted out a workroutine which is more
involved but works just fine.
Thanks for notifying the ExactScan guys and
responsiveness 
Make that “thanks for you responsiveness” 