Although Mark is right about using P-value XML format, GXP, GRP, WP and HT use P-values.
The GHP and GXV can use both.
Not sure why the decision was made to switch when the Grandstream as vendor states P-values.
In any case, you can use GDMS for provisioning. The templates lack a bunch of things we set on Phones anyways, so either we redesign the existing templates completely or just use GDMS.
If you have an older install, grab those files and create custom templates. I'll be using those with GDMS as core P-value and provisioning templates for SIP, BLF and Phonebook, thus customizing the templates just for those.