I realize that a weighting factor of 2 is a conservative estimate, but I wasn't aware research on the subject had been carried out.Bückheim investigated this in some detail. His findings suggest that a weighting factor of more than two would be in order, I think. Do you have AES access? If not I can summarise the findings, if it would help?
I would very much like a summary of the paper. Unless it's of interest to MZKM, maybe another thread would be more suitable.