Thanks.
I saw zero lite effects (I wasn't looking that hard, as I've never had much luck photographing the bats at the Congress Avenue Bridge) and I heard several folks that were looking for the bats complaining about not really being able to see the bats, as they didn't come out until after dark. I had also heard about the light effects, but never heard any "ooh's" and "ahh's" while the bats were leaving the bridge.
It wasn't very easy to move around on the bridge, as the crowd was rather intense in size, as the below photo sorta' indicates.
