I am a big believer in FS lighting when used properly. Unfortunately there are a lot of misconceptions about FS lighting. The first is why it is used. Although many people believe that it is for Vitamin D production, most light manufacturers agree that the UV production is far too low for any real Vitamin D production. Even with the right CRI, Kelvin rating, and UV output, the UV output will degrade so much faster than the tube that most tubes in use don't put out the UV rays necessary for Vitamin D production anyway. Instead, FS lighting is the most beneficial for proper vision by parrots. In short, they see differently than we do-- and the UV output that the lights do put out (a different wavelength from that which would contribute to Vitamin D production) allows them to see properly. I know several people who believe that the reason why birds crash into walls, windows, and doors in homes is because they can't see without the proper lighting.
Second, there are a ton of FS lights on the market that don't do anything. Compact fluorescent bulbs, for example, are not rated to produce the proper CRI nor UV output necessary for parrots. A few off the top of my head, for example... Zoo Med (Avian Sun), Featherbrite, Avilux, Vita-Lite, etc. To truly reap the benefits of FS lighting, you need full fluorescent tubes with a CRI of at least 93, a Kelvin rating of between 5000 to 5500, and a guaranteed UV output of both UVA and UVB.