Hello Dr Rassman,
While scouring some medical journals, I came across this 2007 clinical study that involved a comparison between Finasteride, Dutasteride and a Placebo. The subjects were 18-55. And the study seemed to confirm your suspicions concerning sperm count; however, not to the extent that may have been feared. Please find link below:
Thanks for bringing this study to my attention. What is needed is a double blind approach where sperm count is high on the list of targeted outputs. Without such a study, the safety of dutasteride (with regard to fertility) may be a problem for young men wanting children.