Thanks DanZeal! I've just released 6.6b based on the poll results and the summary from my last reply. I don't pretend that this marks the end of the discussion... in particular I want to call out these more experimental points, all of which can be edited further as time goes on:

• There was not a clear consensus response to question 10, whether there should be + for plus players or - for non-plus players. Like I said, for now we're keeping - for non-plus players, but making sure that - shows up even when the players are still connecting to the server/level, in case that was people's concern.
• Question 12's consensus merely committed to "1.23+ and 1.24+ clients are distinguished somehow" (to server hosts) without specifying how they should be distinguished. Currently this is achieved through the teal color: the player number is teal, the + is teal (if they're running a different plus version), the - is teal (if they're not running plus). Older versions of JJ2+ used both teal and blue for this purpose in different contexts, but that feels over the top, and blue was too easy to confuse with blue players in team-based gamemodes.
• Almost everyone liked hiding the roast/death/etc. numbers for spectators, but there was a free-text answer suggesting that we try drawing - - for them instead of drawing nothing, because it looks weird having empty rows alternate with non-empty rows. That sounded interesting, so we're doing that only when the player list is sorted by player number. Consider the case where player 2 is a real player, player 3 is a spectator, and player 4 is another real player. If your player list is sorted 234, then player 3 will have - - for their stats. If your player list is sorted 243 (or 423), then player 3 will have empty stats. I think this is a nice-looking compromise, but we'll see what everyone else thinks.
• Obviously there was no consensus at all about how to handle long names, so I'm trying a combination of two or three different options. Long names do get tighter spacing but not tighter than ?2. The player list grows or shrinks horizontally based on the longest name, but with arbitrary minimum and maximum widths that I'm sure people will have opinions about. Let's give it a try.

I would again recommend that if you don't trust someone not to leak your IP address, you should not join their server.