At least in the US, LED's so far have been a big disappointment. If you get a properly made bulb, with everything working, it is great. But in the US, all consumer grade LEDs are produced in small job shops in China, where quality control is non-existent. I purchased an LED flood light shaped lamp, and it failed within a week, three replacements within 4 months and still did not receive a lamp that would work for more than 14 days. I will not bother with LED's until they are made in the US, Japan or Germany. The manufacturing quality is simply not there in the Chinese made products and they are not being made in the US, the few US companies selling them have out-sourced the manufacture.
The Sun-Agro HPS (high pressure sodium) lamps were designed to be used as supplemental light for greenhouses in high latitude climates. I have been very happy with my 20+ years experience with these. The 400 watt or 430 watt HPS give good intensity (have flowered Vandas under these in an otherwise dark basement) and the bulbs last up wards of 3 years with serious degradation. High Pressure Metal Halide need to be replaced every 12 months due to rapid fall off of light intensity. So to supplement light in a greenhouse I recommend HPS lighting. The issue of HPS being somewhat heavy in the red wavelengths is compensated for by the natural light that you get during the day in the greenhouse.
Rick's comment about reflectors being important is right on the mark. Check your local brew & grow shop, or pick up a copy of High Times to see the latest in energy efficient reflectors. :evil: