95%+ of male pattern baldness is a result of too high DHT. Suppressing testosterone to female range is the best way to stop the progression of MPB. This is backed up with results from blockers showing that 95% of men experience slowed rate of loss, full stoppage, or even regrowth after 12 months of DHT blockers. Furthermore, there are citings showing that eunichs / those post orchiectomy pretty much all have NO further scalp hair loss (I think I've also read somewhere that almost ALL DHT conversion happens in the testis).
And yes, a very common occurance with DHT blockers is initial shedding (5-10% of total scalp hair) followed by positive results.
I did not have a problem with MPB. The only thing I had lost was the very common frontal temporal corners in a mild - moderate way. I did notice an initial shedding (especially at the crown, which did NOT leave a thin spot at all), but regrowth on the crown and even slight regrowth at the corners occured. In fact, my classmates are astonished by how densely populated my scalp is, so I have gained quite a bit of hair.