Well I am one to suggest never putting any kind of hormone in your mouth because of the horror that my endocrinologist has revealed to me, and I believe him wholeheartedly. I attribute my confidence in him due to the general calmness and lack of any ill mental feeling I have had at any point during my transition- and I am on super high doses of E and P. I am on the feminization fast track, but mentally I seriously feel just as normal as ever.
Soon he is releasing a book detailing all of this stuff. Hopefully it is published soon, because I do not have the resources to completely explain myself. All I know is that the liver doesn't like hormones and it gets the most that way through the digestive tract. I am helping him get his website in order and there will be a lot of information there, too.
Anyway another thing he has told me (because I asked about spiro) was that it's not good for your body or mind at all.. and that only people with highly sensitive T receptors or a high T level should ever need to take it (and a super small dose at that). Most doctors out there are prescribing it to everyone and putting more stress on people's bodies than necessary. It does work, but it comes at the price of nasty side effects.
I bet in the next 10 or so years we will see endos finally getting smart about the way that they prescribe HRT to trans people specifically. It seems like such a specialized thing to do, and unfortunately most endocrinologists just don't have that specialization which is what we all TRULY need.