Even I take Stew's word about studies he saw that prove 5-alpha reductase effect on Trenbolone, and that it does get reduced to analogue of DHN,but it doesn't mean that Fina is safe for hair.
Deca-deffinately.... and relatively, if you compare to Anavar,for example.
But, even if Trenbolone gets reduced to something milder that shit is still going to be strong androgen, don't forget Trenbolone is 3-times stronger androgen then Test 3 and in unreduced state it's slightly stronger then DHT.
Also, very good point Stew is making that Finasteride(Proscar,Propecia) shouldn't be used with Nandrolones(Deca) or Trenbolones(Fina) because it will accelerate hair loss.
So, the formula is simple: stay away from Deca or Fina, use Finasteride(Proscar,Propecia), Saw Palmetto, Nizoral shampoo, Minoxidil(xandrox)