Yeah, I would say that unless a future Korg absolutely blew the T4 away, it doesn't make sense to switch brands when there is such a learning curve with learning a new OS and creating new registration files.
I'm happy for you, Scott. A little jealous that I might have to wait 4 years before the S range of keyboard catches up to the T4. That's a long time!
Enjoy!
Beakybird