Whichever reflectors you used would have to be mounted pretty high for 2 to cover a 6' tank.
This may help. It's Sanjays latest reflector test.
Product Review: Analyzing Reflectors: Lumenbrite III, Lumenmax Elite, Lumenmax, and Lumenarc III | Advanced Aquarist's Online Magazine
"The reflectors seem to fall into 2 separate groups, Group 1, the Lumenarc and the Lumenmax and Group 2 comprising Lumen Brite and Lumenmax Elite. The Group 1 reflectors seem to be better at providing a wider coverage, whereas the group 2 reflectors tend to focus the light slightly more creating higher peak values and smaller spread."
"The Lumenarc III and the Lumenmax reflectors provide a large area of light coverage and hence are more suitable for tanks wider than 3 ft. The reflector will be able to provide a higher intensity deeper in the tank, thus making it a better choice for someone looking to light a wide tank that is deeper than 30", or for providing the ability to grow higher light corals lower in the tank."
"The Lumenbrite and Lumenmax elite are more suitable for tanks 3ft or less in width. They tend to provide a more focused coverage and higher peak values than the Lumenmax and Lumenarc reflectors. This can allow for better use in taller tanks, as more light can reach the bottom, or allow for higher placement of the lights thus reducing the heat dissipating in the water, or allow for higher light values to be obtained lower in the tank."
I'll never get to see the "real" thing. Just the thought of putting on a snorkle gives me a panic attack.
