Well, this is something that many of us have wondered about. And I have a decent amount of experience with both forms, intramuscular and sublinqual estrogens. I have found that I can feel it more in my body and especially breasts when I take orals under the tongue. When I switched to IM, about 9 or 10 months into transition, I was really disappointed that I could not feel it at all...anywhere. So for me, I am right now doing a test by experiementing again with pills and seeing what happens, after about 14 months of intramuscular injections. I do live and work as a woman, but I was beginning to become passable at 5 months. And at that time, I was taking pills. It seemed to work pretty well for me.
But the truth of the matter is that there is virtually no credible evidence that says IM injections are more effective at feminization. Nothing exists that can tell us that, unfortunately. And while I think depot preparations are great, I'm thinking that pills maybe be more effective for me. I am not sure of that yet, but I suspect that to be the case... And I also suspect that this is very much an individually based reality; it works better for some, but perhaps not for others...