Rick3000; As others have said and my observations also support, the Low temp thermostat has no effect on the real world temperature the engine will run at. It appears the cooling system is in balance with the heat output of the engine. My engine gets to the same temps it did before Low temp thermostat install. Now when ambient temps are less than 65deg then yes the engine will also be at lower temps but, Since we are looking for cooler oil in high ambient temps then my thought is that even if my water temp is actually 215 deg, 215 would be a lot better oil temp than the 230 deg+ range without the S cooler. (These temps are clearly best guess since as JFP has made clear the temp gauges are less than accurate). While it may seem putting additional heat in the cooling water would defeat the purpose, I believe the cooler oil returning to the oil cooler would ultimately lessen the BTUs into the water system. All opinions welcome.
As far as 16 year old hoses I replaced all my engine end hoses when I did the cooling system and they were actually in very good condition. still very soft and pliable. SO except for some abrasion on one I think they would have been fine. However if a hose fails when you clamp, it needed changing anyway!
edit; Sorry for rambling. Reread your text. I am considering the mods you bring up. I will say that I like to change one thing at a time and evaluate. This way I know what had what effect. Makes troubleshooting a lot simpler if problems arise. Too many changes at once is hard to determine. So that being said I will do the S cooler first then center rad if necessary. May not to have to do the complex stuff.