Okay, I don't known when I'll find time the next days. So attached the second patch of the conversion described in patch tracker https://sourceforge.net/tracker/?func=detail&aid=3556968&group_id=588&atid=300588.
Attached patch converts all WorkRequest users to the Task API.
An open and still untested problem/point is the abortion or cancelation of a "IOTask". But you will get the idea of the conversion. Please have a look and give me feedback.