I am actually in your shoes exactly. I had years of women's health research, and always assumed I would be ob/gyn. However, I loved my optho rotation and they loved me. An unexpected high risk pregnancy has me doing a research year, and I am still torn. I don't think your concerns about salary are accurate. New optho seems to be fine, unless you are committed to a highly saturated area. I agree that patient panel is better in over/gyn. I find ob/gyn patients some of the most compliant. Hours are much more stable in optho, but the ability to specialize in ob/gyn can significantly affect the horrible hours. Both offer significant chances to make a difference in research (endometriosis/infertility vs. cataract and surgery advancements).
In my case, I may just take this year to see who loves me more.