Enhanced Spectrum High Pressure Sodium bulbs are color shifted to produce more blue than a standard HPS bulb. This makes them great for "one bulb grows all" lighting. They also have great red spectrum making them a good flowering bulb, and additional blue spectrum making them an effective vegetative growth bulb keeping the stems from elongating. Which can happen with standard HPS bulbs during vegetative growth.

I use Hortilux bulbs my self and have great success with them. I assume they are just catching up to the rest of the industry. They noticed a market and then joined in very late. This may drive down the price in the future due to competition, we can only hope. This is nothing new the technology has been around for a while now.