finally, went through the source code a bit. I think it's a bug.
Look up CUpDownClient::GetScore , the credits don't get into account at all.
On a side note: this GetScore function is not used properly throughout the programm. for example in ClientDetailDialog.cpp in the OnInitDialog function, the first parameter of the functions is 'isdownloading' but the function assumes this as second parameter....
I could patch this up if you care, but not until next week....and I should know how the credits are calculated against the other options (file prio, time in queue). Maybe I'll look up in xmule and/or emule.
In any case, the GetScore function should be changed in order for the credits system to work. Right now it doesn't, and this goes against file-sharing philosophy, ain't it? How are credits calculated for the QR in xmule or emule?