Thanks for using the RPS Include Content plugin and for posting your idea.
We used the post id because it is a unique identifier and thus more accurate, plus it works even when “pretty links” are disabled. Slugs can change, although admittedly not often.
It probably would not be a problem for us to add this in some future version and have the plugin continue to fail gracefully, so we will certainly consider implementing the idea.
In the meantime, the post id is easy to obtain with our RPS Blog Info plugin and we recommend using that in conjunction with RPS Include Content.
