I believe the anwser is no, but I want to confirm. If I create a pdf form in LiveCycle Designer, can I load and populate that pdf form with a different library such as iText or do I have to use continue to use the LiveCycle PDF Services. (2.5)
I have also come accross this situation sometime. iText mostly work with Acrobat form. But there is a recent version of iText , I guess it's iText5 which may work in LiveCycle PDFS. But If the PDF is not right protected.
Yes, you can update forms from designer with data from any number of libraries, from iText to the Adobe PDF Java Toolkit to any variety of .NET products. The key is that there are different APIs for the XFA form (you update the XML data stream in the XFA area) and acroforms (where you update individual fields or update through FDF/XFDF import).
Also, keep in mind that a reader-extended form or a signed form should be changed in incremental update mode or you'll lose the rights and the signature.