Hi Martha! I currently support clients on a PEO platform and used to be a client of the competition. LOL. I find that they work really well when the client has an understanding of the product operates and any limitations. When I was a client of a different PEO, I absolutely loved it. The resources and guidance available in a well structured PEO can be amazing, especially for the 1 person HR dept. Many PEOs offer a variety of products and services built into the product line which can make administering a breeze. Additionally, some offer direct resources for employees which can alleviate employees having to contact the HR dept. or employer directly which is also very beneficial!
I suggest obtaining a few references in various industries and ask questions that will help you make the most informed decision.
In my market, clients like go switch from one company to another depending on their needs such as benefits or worker's comp. Other clients have been on the service over 20 years and would make a change unless they closed their doors. If a client is well educated and has a vested interested in taking advantage of all that a PEO has to offer, it can be a great option.
Here some links to give you more information:
Good luck. If you have additional questions, let me know. I'm happy to give you the run down from the client perspective as well as from the PEO itself.