well, i can only tell you about the experience i had when i zapped the tank with new lamps.
the corals seemed unaffected for about a week, then all of the sudden they started failing. the zoas melted away, the sps
bleached out a bit, and the lps
shriveled up and looked terrible.
i don't think i lost anything really. i had some large zoa colonies that were about a quarter of the size when it was all over, but they bounced back with a vengeance. everything else colored back up in the next couple months.