Sounds like you’ve got yourself talked into keeping Renix, which I think is the right call. With Cruiser’s info, it shouldn’t be too hard keeping these rigs on the road. To be honest, OBD1 does not seem like an upgrade over Renix. I don’t think there are as many knowledgeable people in the ODB1 crowd.
I could see doing an ODBII swap for easy diagnostics, but that’s a ton work and if your truck hasn’t had much for issues to this point, it seems like a good way to end up with issues.