I mean, i'm not against that idea, but this place is budgeting/scheduling an upgrade for one of its PLC 5 systems at the end of this year (Yes ONE of, we have 3 more large PLC 5 systems), the SLC 500's will probably have to wait a bit.
Upgrading the SLCs are pretty easy from memory just make remote IO and put the project in a timed scan class. (from memory it's been awhile since upgrading those).
I just didn't like the older platform because the old systems had INT and a weird skip around 8 and 9 bits or another bit jump. This would always cause issues with troubleshooting and cable wiring numbers.
For example someone looking at ####.17 wire but the code was now .15 or something. For the effort to upgrade it would have saved a lot of time to rip it out and upgrade to newer stuff.