Let's just pretend for a minute we totally delete the current survival world, let's say Intelli puts up a world download for it and we have a brand new map.
(This isn't happening.)
Pros: We would gain all the benefits of 1.3, it would be fresh and new, meaning it would be fun. If we went old school and had 100blocks around spawn, then I think we would keep a lot more new guys and easily manage 100+ players all the time.
Cons: People would lose the builds they've spent hours on. All the items we've worked on for ages would be gone, and people would complain and 'quit'.
Here's the thing though, I believe after a week everyone would get over it and find it's far more fun if we had a new map with a new system. Everyone expresses the fact that they are bored with the map, etc etc, although if anyone even mentions the word 'rest' or 'wipe' they instantly threaten to quit because they don't want to lose all their stuff - Which is very understandable of course.
So yeah I'm pro map wipe, just my two cents.
Personally the best solution IMO is to keep the current map, along with a new survival server for 5.0. That way, nobody looses their work and we get a fresh start too. The only problem is extra work for Intelli, but we have perfectly good server (former creative server) for 5.0. So why not use it?
Thing is, the classic server as we had planned would probably average a very small amount of players. Our current server just doesn't pull in new players - A lot of Minecraft players just don't have the patience to go through all the hoops in order to find public land, even as simple as they can be if you know what you are doing.