Your self analysis on Bonvoy sounds reasonable to me. I had to look that card up and YIKES at $450 for that and only coming with Gold which you get from your Amex Platinum. I vote GONE even for $150 out of pocket. Save that money to keep your CSR.

And if you're Delta Silver and predict maintaining it, I'd probably drop the Skymiles Plat card with the upcoming annual fee increase to $250. Of course I don't know what trips you have used your BOGO on but $250 cash can go towards a regular economy flight and not have fare restrictions and earn MQMs.

Amex Platinum is admittedly a PITA to use the credits but Skyclub access and 5x points and the IAP make it worth my time.