I believe your question is based on a misunderstanding of my comments (I'm not a native speaker, so there is a good chance this is a fault on my side).
You write:
During that development process it's come to my attention that my development is apparently following the "old" (Simple Message) interfaces mostly by way of comments about the documentation being out of date. For example, these questions all have answers or comments that mention that the Simple Message interface is old but don't point to the updated info [..]
and:
Unfortunately, I've been unable to find any documentation/tutorial/webpage that specifically details what the most up to date Robot Support Package interfaces are [..] Does anyone have any links or otherwise to information or documentation (or at a minimum a example repo) that details the newer ROS-I Robot Support Package interfaces?
I believe the specific comment that confused and caused you to (eventually) post this question was (by me in #q330389):
Finally:
I'm working on creating a ROS-i robot support package based upon reading their FAQ/Tutorials (http://wiki.ros.org/Industrial/Tutorials).
as the approach that was taken for the older drivers (ie: using Simple Message et al) is not something that is still often being used, those tutorials have gotten a bit stale. They should be updated, or at least their status should be made more clear.
What I meant to say here was (and still is) that using Simple Message itself could be considered "old". Not that there is an "old and new way" of interfacing with robot controllers that are both "part of ROS-Industrial".
Simple Message was really only created as a stop-gap measure, at a time (around 2010/11) when external motion control interfaces to industrial robot controllers were not ubiquitous (or at least not on the controllers targetted at that point in time). It is a very simple, primitive protocol that just serves its purpose (because of the very limited programming and runtime environments these controllers have), until you have something better available to you.
For most industrial robot controllers, "something better" has been available for quite a few years. KUKA has (and has had) RSI, FRI, SmartServo, DirectServo, EKI and some others. ABB has EGM. Fanuc has Stream Motion. Mitsubishi has MXT. Universal Robots has RTDE. Denso has b-CAP. Kawasaki has KRNX. Etc. Etc.
All of those interfaces support external motion control orders of magnitude more comprehensive and performant than would ever be possible using Simple Message (between 100 to 1kHz position, velocity and sometimes even force/torque control). And best of all: all of those interfaces are supported by their respective manufacturers. Some will even let you use those interfaces "on the factory floor".
From that perspective it doesn't make much sense to keep using a custom, primitive protocol -- if you'd target those kinds of controllers.
If you don't, and you don't have a good, performant external motion interface available, then using Simple ... (more)
You might also want to submit this to the ROS-I Issue Tracker on Github.