in versions i've played (not played a version of zig in a good month or so), the only issue i've really had gameplay wise is the forward exit for blue getting pyro camped. it was mentioned by others as well, so i think you're already aware of that, so it's probably not an issue anymore.
I never really noticed snipers abusing long sightlines myself, although thinking about it once the setup gates are open, blue are a little exposed as they approach the gates from the spawn area but only from red players that are at certain angles, and the red players don't have any health/ammo nearby to keep them there, so it's probably not an issue to be concerned over.
(just saying that maybe the sniper issue isn't as bad as it seems, perhaps it was player-related more than map related?)
detailing wise, looking strong.
personal preference: i'm not too keen on all the lil black spots you've got on the rock textures, but i'm guessing that's just me as i've never heard anyone else say anything about them.
other than that, you need more cardboard-box filled bodies of water inside of cave systems. XD
i may have just had bad luck to miss the tests of the other stages. how are those coming along? will they be in the contest entry or are you going to settle with a single stage map for the contest and add the other 2 stages later on when you have the time?