How long have you been on finasteride? Why are you thinking of switching to dutasteride?
I spoke to a hair transplant surgeon today and asked him about it. He basically said that dutasteride was well tolerated long term in men with Benign Prostate Hypertrophy and there doesn't appear to be any long term side effects. If you're worried about your prostate (and it's a strange thing for a young man to worry about) then don't, dutasteride is specifically marketed as a BPH drug so it should actually lessen the potential for future prostate problems, not enhance them.
The greatest risk with switching to dutasteride is upregulation, that is the hair follicles becoming more sensitive to DHT to to the DHT blocking effects of dutasteride. With finasteride it's more cyclical due to it's short halflife so upregulation is less likely to occur as levels go up and down every 24 hours, whereas the consitant presence of dutasteride due to it's much longer halflife may mean upregulation is more likely to occur since the follicles are consitantly subject to much lower DHT concentrations.
Of course there's no actual evidence that upregulation occurs at all in hair follicles due to DHT blockers, it's just a possibility. That said, I'm also strongly conisdering switching to dutasteride. If upregulation doesn't occur (and we really don't know) then long term, dutasteride is by far the more effective of the two drugs.