Yes, I think PG has plenty of food for thought 
After doing this workflow for awhile, anything else feels too kamikaze style. I like to be easily able to get back to the source for any given moment to compare, and maybe redo that small section.
I’m surprised the RX app doesn’t let you do this when working with an RX doc. I’ve heard that CEDAR can do this but I don’t own that.
For me, it’s all about seeing what you’ve done, and having the flexibly to go back when needed, maybe reuse part of an old RX fix combined with a new file, etc.
Even if I stopped using REAPER for the analog processing, I may still use it just for this workflow alone. It can be done very fast even though two apps are involved. It’s similar to Pro Tools AudioSuite or maybe Cubase Direct Offline Processing except you get the added bonus of the spectral view when doing the small spot edits.