you should be able to keep some SPS
close to the top in the area of the actual fixture.
i honestly think T5s are more intense lighting then other style lighting and since a lot of people have been able to keep maxima clams under a 4 lamp t5ho i wouldn't doubt that they can grow SPS
especially with a quality lamp like ATI, KZ or gueismann
does the fixture have individual reflectors for each lamp or is just one or two