A quick update. I noticed a post in another group about iTunes 11.4 & Snow Leopard not working with iOS 9.
Re: After iPad iOS 9 update you can't use 10.6.x
I took a chance with an iPad 2 I had at work. It actually only had iOS 8.0 on it, so I used the IPSW file I downloaded to update it to iOS 8.1.4 with iTunes 11.4 on Snow Leopard. I ran a normal backup and disconnected the iPad. I ran the iOS 9 OTA updater from the iPad. Once fully updated & basic settings looked over, I connected the iPad back to the Snow Leopard Mac and it was recognized. iTunes 11.4 backed up and synced the iOS 9 device, both over WiFi and wired connections.
When I got home, I took the chance with my personal iPhone 6. Everything worked the same as the iPad. iOS 9 is now running on my iPhone 6 and it will still sync with my Snow Leopard laptop with iTunes 11.4.
Of course, the usual YMMV. Apple won't be signing iOS 8 for much longer so if one needs to revert back, that window is probably closing quickly.
Yes, I've taken my chances as and iOS 9.0.1 update may break this all over again and I won't be able to use my current setup, but I have a plan to deal with that if it happens - a Mac Mini with updated software to keep our iDevices synced.