I have two identical scenes, one in BI and one in Cycles. They both have point lamps in the same place (or, in the case of a linked scene, it's the same lamp with different settings in each). The BI lamp's strength is controlled by the Energy field. The Cycles lamp's strength is controlled by the Strength value of it's emission node. They are both pure white. All other settings are default.
What values of Energy and Emission strength will give me the same amount of light? Will other settings, such as Size in Cycles, change this? Does it depend on materials (assuming no other emitters/lights, or reflective surfaces, etc. Light bounces will also make a difference, but we can do this without those for now.)
For example, my Cycles version currently has an emission strength of 500. My BI version has energy of 1. The BI lamp seems to be significantly brighter than the Cycles!