Bushfiva,
I think that we are talking about slightly different things - you are looking at the total loss over wireless, I am just looking at the difference in loss between encrypted and unencrypted.
I can well believe that the total loss of an encrypted wifi link is 60%.
The maximum capacity of a shared half-duplex wired ethernet network is - at best - 2/3 the nominal capacity. This does increase to about 80% in a full-duplex switched environment - which a wifi network can never be.
SD