Our Main reef runs 10k 250w Reeflux bulbs driven by Icecap e-ballasts.
The FOWLR runs 5 x 54w T5's not overdriven (standard ballasts, not IC 660's)
Even though it's a FOWLR, we trade stuff back and forth between tanks. Things like our green and pink policipora love the T5, and actually grow as well, or slightly better there, then in the main tank under MH's only.
Acro's, Hydno's, etc, do a touch better growth-wise under MH's, but still stay alive, and do just fine under the T5's.
Also remember that these two tanks are not on a common sump, so they do differ in water params from tank to tank, so my observations are not of a direct identical setup where lights are the only difference.
~Kurt