I purchased 4 used R500 Access Points about a year ago, all of which were stand alone versions, and I flashed them all to Unleashed and they all work great. I'm even using the Mesh feature on two of them. You are however limited to the version of firmware that you can install because beyond a certain version, R500 AP's are no longer supported in the latest versions of Unleashed. Check the Firmware Notes for the version you need. I'm currently running 200.7xx.xxx.xxx and they just released 220.127.116.11.121 which I have not pushed out yet. I'm using them at my home and they work perfectly!