Iron Grinders: I think the cost structure is fine, though I personally abhor wither skel farming, which is the primary cost right now. The costs aren't too hard to find, though new players might be confused by the alert/imgur link setup. I wonder how hard a searchable help function would be to make, "/helpsearch grinder" giving you a list with iron grinders, grinder rules, etc to choose from and see; so we could bring all the rules in game and into one more accessable command.
Nether Portals: Good number for this size of map, and easy to find in the initial rush. I'd still prefer a plugin that allows mods to 'link' portals manually, letting us get closer to the vanilla system.
The Nether: Standard nether is all sorts of boring to me. I liked the custom nether from the few previous revs, but wouldn't mind some more cave/mountain-ness to bring it closer to the vanilla style.
Map Generation: Map size is fine, custom biomes are alright, but distribution should change a bit (Less floating islands and clay mountains?) and larger biomes would be nice. As far as water, I'd like only one smaller ocean, possibly a corner, with plenty of large rivers and a few lakes. (No clue how controllable terrain gen is for this)
Ore distributions: Gold, gold gold gold, and gold. Seriously though, not a huge fan of the 'everywhere' ores. I'd like to see each biome have its own strata combined with the boosted vanilla ores; say swamp has lots of coal and iron from surface down, with only normal other ores, and mesa would have boosted gold from y40 to map height, but lower/unboosted levels of ores otherwise (including normal gold rates for lower y levels as if another biome), Extreme hills could have y50+ emerald ore and slight diamonds added, etc.
MapWorld: As nice as the map tiles can be, they've always seemed like too much work. Also, no floor/ceiling placement is a bit of a dealkiller. My ideal, pure fancy, would be to see an external program that palletizes images into the 16,384 byte map color data, which could be uploaded and saved as a map super easy, and then be bought with an ingame command.
Miscellaneous: For the test world, if and only if you can manage worldedit, like C proper. Blogposts were nice as they are.
Spawn: Current spawn is good looking, but a bit annoying to get around, has no stables that I saw, and generally lagged my comp. I'd like a return to a smaller spawn building, akin to rev 2, perhaps with signs used to warp to tutorials / etc elsewhere. Surround it with a lot of curated plots that are given out during events and the like for players to show off their best work in a spawn theme.
Special spawners: I like the 'natural' spawners and their structures added by biome bundle, though the 5+ spawner dungeons/grinders are a tiny bit ridiculous. As a special spawner locating expert, I have to say I really dislike the current hidden sign approach. Too much luck and terrain scanning, no real challenge except time. I know it requires a large amount of admin effort, but I'd much prefer an exploration quest or something that runs in episodes for the first month or two, or perhaps a system like iron grinders: Naturally occurring mobs of each desired type drop a ' <monster type> core' at a much rarer rate than EoF, which can be used like the iron grinder system (but only leveling up to the power of a normal grinder). If worried about too many spawners over the rev, have each core dropped/used lower the drop rate a tiny bit, and keep them 200+ spaced out. As for added spawners, WITHER SKELETONS. I hate hunting them.
Events: I'm not a big event player, but I don't mind anything listed being part of the server culture. Though I did have some issues with the fundraiser maze event; the inability to worldedit was annoying, understandable for the weird P creative 'worlds' setup, being also unable to use C for it less so. Far more bothersome was that I gave nearly a week for any sort of feedback on my completed maze so I could correct any problems for them, and so the maze checking operations could be spread out more; however, I heard not a word about it.
Closing Thoughts: Seems to be going well, I hope the uber project finishes.