I have a set of PDF files that were created in Acrobat Professional with fillable, savable forms. I can modify the values of the fields in the forms, and save those changes with ABCpdf, which works great. The problem is that users with Adobe Reader can no longer save any data they put in the form. They can still fill out the form and print it, just not save it.
This might be licensing related (on Adobe's end), but I have not been able to find a solid answer one way or another.