This thread may be of interest if you have T5s and want more light out of them. It is off a marine fish keeping website, bit the principle of over-driving T5s is there. This is something I am thinking about doing.
I was thinking it may be useful for people who have taller cases, that it may get stronger light further. Say for higher light needs plants like vandas.
I agree, normal T5 would be fine for most growing cases though.