It's not a direct replacement but it works good.  The Picostation was part of the AirMax product line.  I never had good luck using it as an AirMax AP and getting decent results.  If I used it as access point I flashed it with Unifi firmware.  The "drawback" is that you have to install the Unifi Controller to be able to manage it.  Originally this scared the snot out of me but now I have it running at a dozen locations and love it.