Yes, you need to know whether (work via agency - their cut) is going to be greater than (work independently). There is no way to predict that - obviously agencies say they are busy, but it's not a problem for them if they have more people using them to find work than there is work for them.
Given that you're at risk of arrest etc because of the stupid sex work laws in the USA, how much do you trust an agency to get the screening right? They are likely to be a much bigger target for the police than a lone independent too.
In terms of physical safety, agencies tend to send people to anyone who calls. It's not them going there. Outcalls are not necessarily more dangerous, if you have a proper security setup and the client knows it.
Keep some records! As well as helping with the business, it will help when it comes to paying tax (if you're not, you're more likely to get into trouble for that than the prostitution).
Have you considered asking an agency to find you some work while continuing to work independently?