I don't think it's an easy question, as LED's are not built equal. I'll never go back to old tech, but I also went with 5W and 3W CREE bulbs, I'm thinking if I had gone with one of those underpowered fixtures (especially the early ones) I likely would have a different opinion.
Reeffreak has seen my setup, it's 100% LED, and I'm pretty sure he can attest that I have good sps growth, and it has been 100% LED since the rebuild...
That said, I don't have anything against T5, I have thought of adding a couple of bulbs for 'showtime' but I don't have room in my hood (for now). I wouldn't run them except for those days I'm sitting there tripping out over the colours in the tank
