Like anything there is a bit of a learning curve when moving to LED from HPS, the plants do not respond the same ways. Because LED offers a much broader spectrum of light more elements of photosynthesis are going on in relation to plants growing under HPS. What is typically seen is a greater usage of calcium, but I will say that your plants do not look calcium deficient. As for your hairs, they have no bearing on whether or not your plants are done, it should come down to trichome production and maturity; so using them to determine how finished your plants are is inaccurate. I am sure you know this, but are still looking at your plants the same way you would as if they were grown under HPS, this is part of the shift in mentality when growing under LED.
As for the purple showing, all plants are capable of going purple, it is due to the production of anthocyanin. Technically anthocyanin would count as a terpene, and LED lights seem to bring out greater terpene expressions. So seeing the coloring come in is not abnormal. The production of
terpenes will have an effect on the flavors and effects of your final product. So, if there are effects or flavors you were not expecting this is likely why you are experiencing them.
Also running those lights 30 inches above the canopy seems quite far for LED units. I know you saw some adverse effects early on, but typically LED units are run closer to the canopy than HPS would be; at the end of my runs my plants are less than 16 inches from the top of my plants, and with one of my units I like to have the plants finish between 8 and 10 inches from the tops. On your next run you may actually want to experiment with keeping the lights closer to your plants and see how that works for you.
One last thing, your plants do seem a bit green for harvest is that normal for your grows? A bit more of a flush may also aid in your final product.
I know you are no newbie, but you are definitely charting new territory for your grows. So keep at it and keep trying things out, but I think eventually you will find what works or you and your plants.