increased flow in a radiator does decrease cooling capacity. i am not nearly as advanced as those who have spoken above, but the graphs in BillA's test show that most radiators lose cooling capability at higher flow, except for two. the big momma he tested, did lose some, but not much, dissipation capabilities. the serck he used increased dissipation as flow was increased. you can see it here:
http://www.overclockers.com/articles481/index05.asp
its the third graph down. as you can see, the big momma didn't lose much as you increased flow. the serck, with more air flow, increased dissipation as you increased the flow. i can't comment on his testing procedures, and if it would satisfy you guy's standards however. although i do remember him as being a pompous advocator of testing methods.