It makes sense that PNGOUT would delete it since animations are not officially part of the PNG specs, instead they are present as custom data blocks in the PNG file, and is simply ignored by applications who don't support it. Apparently you can pretty much include whatever data you want in a PNG.
As for that Shadow Man map, at least with only having to animated color cycling, it's a lot easier to assemble the map instead of having to capture it completely multiple time.
Animated maps really aren't practical, especially if parts don't cycle with the same frequency as Revned said.
Personally, so far dithering is fine so far, with the occasional use of transparencies when dithering or pixelated effects just don't do justice to the graphics (like my still-unposted Mega Man ending maps).
I might play with the brightness with my last Bucky O'Hare map, Salvage Chute; Acts 7, 8 and 9 go completely dark after a few seconds and only a couple of passing fireflies show you bits of the level. I could show the rooms fully lit as they first appear, but I'd like to actually darken the room but include the fireflies and the bright spots behind them.
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Current projects: Bucky O'Hare (NES), Metal Storm (NES), Clock Tower (SNES), Ristar-The Shooting Star (Gen), Sonic The Hedgehog (Gen), Sonic CD (Sega CD), Mega Man Zero (GBA), Battletoads (NES)