I'm going to get a tad pedantic for a moment:
The current setup
has mobs, because "mob" means "mobile" - i.e. any moving creature (or "NPC" then).
What it doesn't have are hostile mobs.
(Well, it has wolves, who are sheep-hostile and attack players if provoked; and it doesn't have endermen who are neutral unless looked at, but "hostile mobs" or "monsters" is sufficiently descriptive/accurate in this context - simply saying "mobs" is not.)
Nerfing the monsters is stupid - you might as well disable them entirely - a creeper explosion destroys at most 5³ blocks, so it's not a lot of effort to re-build.
But anyway, that's the point of my safe zone suggestion - to prevent hostile spawning without having to place torches everywhere. You can add explosion protection to that zone too, if you're really wimpy, and paranoid someone might lead a creeper back.
:P
Even if it's not feasible to run multiple maps on the server (i.e. insufficient hardware), the old one can be archived and probably even made available as a download, so nobody has to worry about their old creations. (Would be nice if they could both be run side-by-side though, so people allergic to monsters can use the old one
:P)
EDITED: 18 Dec 2011 23:55 by BOUGHTONP