I think it depends on the lights you're coming from and the lights you're going to. When I first went LED, I didn't notice much of a difference on my 55 gallon aquarium, mainly because they weren't bright enough (initially two 18" Marineland Single Bright lights, then I added two more). Then, I upgraded to a brighter light (a single 48" Marineland Double Bright) and used the others on smaller aquariums. I noticed some small improvements in growth, but I realized I wasn't providing enough light for substantial growth. About six or eight months ago I added a 48" Current Satellite LED+ and have noticed a significant improvement in plant growth. So it's not just that I went to LEDs, it's that I went to the proper amount of light. I could have probably achieved the same results with higher intensity fluorescent lights, too, but I liked the idea of using less electricity and producing less heat with the LEDs. They've made some great strides over the last couple years, but they can get expensive for very high light models.