Most experts agree that too much DHT is a leading cause of BPH so you should reduce your DHT (which metabolizes from T). IMO, these experts aren't good to listen to.
DHT is required to maintain healthy libido and overall sexual functioning.
I also do not think DHT is the primary cause of BPH. The DHT levels in young men are sky high, yet how many of them actually have BPH? Not many--these symptoms don't start appearing until men start aging (weight gain? cortisol productin line metabolism downregulation?).
I acknowledge that reducing DHT will reduce BPH (at a high cost to your well being) but I strongly suspect it is because of other mechanisms that are at play and are also affected by the reduction in DHT. I think cortisol and E2 are the most likely candidates.
Do some legwork on google trying to correlate lowering E2 (estradiol) with improved BPH symptoms. Dr. Crislers forum has a god thread about improving the cortisol production line in order to keep T form dumping to E2 and allowing it and DHT to wreak havoc on the prostate. I'm sure at some point I've come across literature suggesting the same.