I am using Org-mode to organize my contacts following
org-contacts.el[1] and a *lot* of additional properties. Those
things are so far »by convention« and I always wanted to sum it up
on WORG but did not find time for that.
Even with BBDB there are only few "standard" fields, and a tonne of custom fields. If conventions are only in naming the property fields that is trivially fixed through a config file (something I do already for the BBDB handlers).
If you are interested in writing a sync module for Org-mode as well,
feel free to contact me. I am happy to describe you how I am
organizing contacts using Org-mode.
I am a beginner level org-mode user - I was away from Emacs for nearly 8 years and returned to find this fascinating and gigantic new development in the Emacs world :) But if you can document your contact structure, I could potentially implement it some point in the future.
Do you use any import/export/sync code with org-contacts?
-Karra