The added blue spectrum WILL increase the qaulity and resin on your buds. Last year i used a 1000 watt HPS and added in a 250 watt mh during the last 2 weeks. Definatly frosts your buds up and gives your plants a more balanced spectrum of light.

Ive also supplemented my 400 watt HPS with 6500k T5 bulbs during all of flower. The buds closest to the blue bulbs were smaller, but had more trichomes.

Go for it!!