BPM: there are a lot of different ways to skin a cat, and I think that holds true for lighting. The 4,100K light range might be a good mid-range lamp to add between vegging and flowering. Here's an example of what a friend who also uses T-5's suggested and I may try it on my next grow. He uses a massive T-5 fixture that either has eight or ten tubes and two on off switches. It's four feet long and it comes out of the box with half 6,500K blue grow lamps and half red 2,700K flowering lamps. Their selling point is that it gives your plants a more complete spectrum. The inclusion of your 4,100K's might make it even more complete.
He starts out with the brighter 6,500K blue grow lamps for vegging in all the receptacles. After about a month of vegging he starts swapping out the 6,500K's with red 2,700K flowering lamps. But he does it very gradually. This goes on for about ten days, with him removing the 6,500's and replacing them with 2,700's at one or two at a time. He claims that this gives his plants a very gradual light change as it occurs in nature. Eventually, they're all the 2,700K's for flowering. It makes sense to me but again the inclusion of your 4,100K's is something I'm going to bring up to him to see what he thinks. What do you guys think? HSA