The advantages, as far as I know, are as follows:
1. Better inhibition of BOTH types of 5 Alpha Reductase, and therefore, inhibition of type 1 and type 2 DHT. Finasteride only inhibits type 2. Dutasteride inhibits up to 90% of both DHT types; Fina does something like 50-70% of type 2.
2. Potential for less than a daily dosage. There is a fairly well know example of a "beta" Dutasteride user from hairlosstalk.com - Dr. Monahan. He claims that in 6 months of usage he went from an advanced N4 to an N2. He also claims that Duta did indeed regrow his temples, but like Fina it was more effective on the vertex. After six months he dropped the drug, and was able to maintain this supposed regrowth with Fina and I think an occasional Minoxodil application.
3. According to Glaxo, users reported 150 more vellous hairs than fina users.
Not sure if they also used NANO shampoos like the Fina trial people did. Still, it sounds very, very promising...