Putting around the server now, and it feels good. I peeked underground in the main part of old Cashout Cove, and wowzers, those new caverns run deep and do appear to have generated pretty cleanly with the existing world! I may have to go spelunking soon.
I also noticed that some of my magic command blocks around the world have broken with recent updates. I guess 1.17 or 1.18 had command some syntax changes. I'll be fixing the "suit up" buttons in my house attic shortly (does anyone else use those?) and will be on the lookout for any other magic command blocks.
Does anyone else here remember where some might be, or have you encountered any that you can confirm to be working or broken?