Zedwick, I first want to say thanks for all you're doing to make the server a fun place.... I can see the quandary you are in, and I promise you all of my catlike rage is directed at Mojang, not you...
The dilemma: Update and risk issues that could run off the veteran players who have poured literally thousands of hours into the server. Don't update and risk new players not being as interested.
I think, sometimes it's less what is best for the people and more what is best for the server. New players joining is very important. As is keeping veteran players coming back.
I know I have worked hard and built up a base that some say rivals Spawn in less than a year. I love my base, it really is my happy place. I would be devastated if any of it got corrupted. And to be completely honest, I cannot guarantee I would return to the server if such a nighmare of a thing occured (in an irreversible manner).
However I know this is not my single player world, this is a SERVER and I realise how important it is to move forward as a server and make it a pleasant gaming experience for ALL, old players and newcomers alike... And the fact is, we are ALL hyped for 1.14 (THOSE LANTERNS THO!)
My best shot at a solution (I'm a dumb cat when it comes to these things) is to make backups of the server as it is right now and grit our teeth and try the update. And if things don't go well and Zedwick's beard causes a nuclear apocalypse, we can use a little beardy magic and restore the server back to it's previous state in 1.13...
I hope my rambly and barely coherent cat gibberish helps even a little in the way of community feedback...
*places a daisy in Zedwick's beard* (thunder crashes ominously)