I would try to concentrate on getting a good and consistant grow before I would begin to foray into additional UVB and the like. I don't use LEDs but use the Eye Blue
Hortilux during veg (along with a MS-1000). For flowering, I use a 1000w HPS and a MS-1000 with xtra red. The combined effect of the two different bulbs was considerable.
Regarding your trichomes not turning milky...I usually let my plants go until they can't go much more, especially Sativa based strains. With a lot of Sativas, you will have a light yield if you follow the typical "recommendations" for using the trichome colors to tell you when things are ready. I gain a lot of potency, color, and a LOT of flavor by adding a week or two of extra growing time. The plants will pretty much stop on their own when they are spent, and a lot of leaves will turn yellow. In my opinion, I have not ever noticed any difference between plants that were harvested late instead of "when recommended". If it was a car drag race, the difference might be a few hundredths of a second faster, but that's about it.
To get the best effects, you need to have the right seeds. A lousy, low level seed might produce a huge and wonderful plant, but unless the genetics are correct, the potency won't really be any better.
What has always puzzled me about the claim that the trichomes produce the THC in order to protect itself from the UV radiation. While I don't dispute any good studies that have shown a link between the two, I don't understand why the plant would produce the most UV blockers during the time period that the UV levels are declining, later in the season. Obviously this is a moot point, especially for indoors growers, but it has always made me wonder if it didn't evolve for some other purpose, like to get sticky to aid in pollen distribution.