Ursula, I'm a scientist, and I know that all these parameters should be taken and weighted
This is not what is important from a user point of view: the user will have a feeling that an app will be faster than an other and it is subjective, however he will choose one. Why do you think shareaza displays bandwidth in kbs instead of KBs? It makes think users dl go faster. Why do bearshare shows 1% dowloaded of a file at the very moment you get the first byte of a download? Also for the speed feeling. What I say is that every users should make their mind by trying competition and then have real (read subejective but important to them) reasons to use a product instead of an other.
EllisD post your findings please they might differ than mine.