You could certainly get some bleaching of even Acropora sp. at 16" depth with 8 HO T5s - especially if not acclimated properly. And especially if a quality fixture with active cooling is used.
Steve,
That quote you were asking about isn't from the article. The PAR of 1100 is from the article but the portion about 2 x 250W MH producing this comes from Apogee measured values from a hobbyist's tank. While 1 250W MH produces the values you've reported the cumulative effect where they overlap with 2 x 250W MH could certainly produce that level of PAR at several spots in the tank - especially with a high quality reflector. For comparison see the picture below where 6 x 39W HO T5s in a crappy Tek light produced the PAR levels seen in the picture:
http://i85.photobucket.com/albums/k72/jartanyon/par.jpg
Fijiblue, the same hobbyist who was running the T5s in the picture above decided to try MH again with 2 x 250W MH over that same tank and found he was getting over 1100 PAR
at the surface.