The research I've done has led me to believe that the results stay for life in excellent responders and in people who responded quite strongly, there may be some minor thinning in extra sensitive areas which isn't troublesome and can also be rectified with a small transplant session. The key is to get on it early and unless you are one of the 2% of aggressive sufferers, it will prove to be life saving. The forum will have selection bias of negative results as people got on it late (it's hard to reverse serious miniaturisation, fibrosis and balding) or may be they got sides/didn't have access to the pill.
I'm at the 4 year mark almost exactly now and haven't lost anything - the first year is an indicator of future prognosis as the trials show.