Jean-Francois, I can feel the difference in the beard when it is properly prepped, however it gets there. I like it HOT, but even after a shower, I think my beard is just about as prepped as it is going to get. I don't know if there are distinct levels of beard softening, but it just might take a little longer with cold water than with hot water/steam. I don't seem to have the patience to leave a hot towel dripping into the sink for two or three minutes, but imagine it could make a difference. I am sure this is one of the reasons every shave is a new experience.
As far as edge retention is concerned, I don't think I have ever come close to really dulling an edge without taking it back to the hone. Honers and shavers, again. I only grow a beard to check my last sharpening, but love the shave when it is done.
Cold water? You don't beat your back with whips during Easter or anything, do you? D