Was showing someone the tech info on the Envirolite homepage yesterday and there's a very interesting paragraph that has been added at the bottom of the page since last time I viewed it.

It seems that independent research is being done by Sheffield University to finally decide wether HPS or CFL is best. They say they are 'extremely confident' of the outcome.

I was already convinced, but maybe soon even the HPS brigade will begrudgingly acknowledge that CFL's are worthy of more than keeping moms and seedlings alive.

Full text here (last paragraph):
http://www.envirolites.co.uk/lightinfo.html