Basically there are no long term studies using estriol and there are not likely to be any in the next few years. Therefore estriol did not show the same increased cancer incidence but only because it had not been used very much for hormone replacement and therefore it was not studied. Only non-scientific thinkers would conclude it was safer. Remember that they are protective against colon cancer, heart disease, Alzheimer's disease and osteoporosis. However, none of the estrogen products seem to have less bleeding problems than others.
Progestins seem to give mood side effects in many women.
They just do not feel well. In that study, progestins caused more breast soreness than natural micronized progesterone but did not seem to show a difference in anxiety, cognition, or affect. More work needs to be done in this area, however, because it is a major reason for hormone replacement difficulty. Since heart disease is the major cause of death in menopausal women, The greatest benefit of estrogen replacement in terms of lives prolonged is the use of estrogens to prevent or delay the onset of heart problems. Again, we do not know that any estrogen preparation is better than any other in preventing this.