US immigrant visa VS work visa

My girlfriend is a nurse. She has an ongoing application for an immigrant visa with the help of an agency. Due to delays in the visa bulletin, the agency offered her the option to apply for a work visa in the meantime. The agency assured her that her immigrant visa application will continue to be processed and that their ultimate goal for her, as stated in the contract, is to obtain a green card.

Before my girlfriend makes a decision, she would like to know the potential downsides of choosing the work visa path while waiting for her immigrant visa. We are aware that the main downside is that her years of working under a work visa will not count toward her residency requirements.

I just want to know if there are people here who tried the same path. What are other concerns or factors that you considered before agreeing to the offer?