Today I substituted a Zoomed Ultra Sun for a Flora Sun in my veg mix. I was kinda thinking that it was a similar spectrum to most 6500K's which people have reported good results with. I immediately noticed that within an hour, the leaves stood up, reaching for the light. I had seen this in some early pics on this thread. I interpret this type of phototropism as a good thing, though I suppose I could also take it to mean that the plants are reaching upwards because they are deprived of something. I cannot speak for any increase in growth yet because it's only been about 12 hours since I stuck it in, and it's only 1 bulb.
I think those including 6500K type spectrum in veg might be onto something. Not entirely sure about flower. I know that the pr0f doesn't really care for those bulbs, and I understand why, but I can't argue with what I have observed. I will update more about the growth as time passes. In looking at the spectral graph of the Ultra Sun (much like the 6500K) it does seem to be less than optimal. In fact, as far as PAR goes, it wouldn't even make my top 10 list. So it is a bit counter intuitive that this bulb would trigger any kind of growth surge or provide any benefit at all in the face of all these other superior PAR bulbs. Yet of all the combinations I have tried, it was this bulb that made the leaves stand up. Perhaps it is only one peak in there that is causing that to happen, and maybe this peak is also present in some of the other T5's I haven't tried e.g. 75.25, Fiji, 454. This might explain why others experienced this phenomenon. I'm not sure what it is about the Ultra Sun that the plants seem to like (or hate depending on how you interpret phototropism), but it has clearly elicited a response from the plants.
I'm not advocating these bulbs...not yet anyway; just thought I'd note the observation.