Knowing that a benign serous cystadenoma of the ovary rarely morphs into cancer- is there any greater risk, outside of this-of getting ovarian cancer as compared to a female without a history of this? ovary still intact that had cyst?

A female without an ovarian cyst is safer than with a cyst which can get bigger and become symptomatic. Regarding serous cystadenoma: "There are no data regarding the decision to observe or remove these benign-appearing cystic masses if they are asymptomatic. If the patient is a good candidate for surgery, it is reasonable to remove such masses due to uncertain future behavior" by UPTODATE.