Higher light = better growth for me but I like the look of the green base with the slow transition into red better.

This is what convexa looks like in my tank under a T5 MH mix positioned in the top 1/3 of the tank. As you can see there's not much green and this piece isn't fully colored up yet, it should get a brighter red..
http://i65.photobucket.com/albums/h2...02/convexa.jpg