The relative safety of oral versus transdermal hormone therapy is something we didn’t discuss, and the authors’ book, Estrogen Matters, doesn’t directly address it either.
This is a timely question. The British Medical Journal just recently published a large study about route of delivery of estrogen. Their conclusion was that transdermal treatment was the safest type of hormone replacement therapy when risk of venous thromboembolism was assessed. Transdermal treatment appears to be underused, with the overwhelming preference still for oral preparations.
That being said, for women with very low risk of blood clot formation/thrombosis, the risk for oral estrogen is very low, especially for someone like you, non-obese, non-smoker, no hypertension, not sedentary, etc. So oral HRT would take a very, very small risk in you and make it a bit higher—but still very low.
The other implication of oral estrogen is that it lowers your circulating testosterone. We (postmenopausal women as a whole) already have low testosterone levels, and, in theory, we don’t want to make them lower. For most women the oral estrogen reduction of testosterone is not clinically noticeable, but some may find it harder to experience orgasm or have lower libido.
I hope this is helpful in considering your options!