Lowering your testosterone cannot be good at all, its the conversion to DHT and aromatization which is the problem, if you start lowering your test levels by ingesting estrogen enhancing chemicals you're gonna mess up your hormonal makeup.
Testosterone is the hormone that makes you feel really good, keep the levels high I say if you're a man , actually women really need test levels in order to feel good also. IMO using propecia or any other drug that manipulates your hormonal levels can only lead to potential problems in the long run.

It's up to you but I'D stay away from the stuff, go with a Toplace hairpiece any day instead