So, when you have a SharePoint Scanning application, why would you want to OCR PDF files?
I am seeing Microsoft SharePoint utilized more and more as a true document management / document imaging solution. There are many document capture applications that provide the ability to scan, capture, index and OCR to PDF . The advantage of the image with hidden text PDF, is that if you enable the PDF iFilter (how to enable PDF search in SharePoint ), you have a fully text searchable body of documentation. SharePoint OCR is becoming a requirement.