Hi All,
Being the author of this plugin, I'd appreciate the support of a purchase, but if you feel the need to grab a modified older version for SEBLOD 3.x and Joomla! 3.x I am not stopping you, but don't expect support.
To answer your question about the article ID, SD Field Concat will handle new articles perfectly fine. It queries MySQL to get the next auto increment value of the #__content table and uses that. It also stores these values in the increments.ini file bundled with the plugin, acting as a cache for future re-use...
To use the article ID, you would concatenate this phrase: "<id>" with any other field. So assuming I wanted to concat an Article ID and the title, my full concat list of fields would be:
<id>||#art_title#
I hope that clears things up? If not, shout and I will explain further.
Regards,
Simon