@farmerman,
No, the S9 is pretty much like the S8 (which my wife has), slightly better camera, better placement on the touch sensor. I think the new S20 has the multiple lens camera. The 600Mhz band is only noticeable if you travel through rural areas and mostly on T-Mobile who is leading the charge to fill gaps in their coverage. (That's the old UHF TV spectrum.) When I travel across NC, there is a stretch of US74 where it makes a difference. 600Mhz is still pretty new, so it could be an improvement going forward.
My S9 is great, the pictures are great. My son has an S9 also and his nature pictures are absurd they are so good. I guess you can always get a slightly better camera, but I wonder if we're at the point of diminishing returns.