The phrase "not without reservations" is often used to express alternative viewpoints or concerns about a particular situation or decision. There are several synonyms that can be used to convey a similar meaning, such as "with some misgivings", "with some reservations", or "with some qualms". Other phrases that have a similar connotation include "with some hesitations", "with some doubts", or "with some uncertainties". These synonyms can be used interchangeably to convey the idea that a particular action or decision may not be entirely without consequence or risk, and that there are valid concerns that need to be taken into consideration before proceeding.