Do all Airport Express generations support client mode + Airplay? I basically want to achieve what is explained in this question/answer.
I have an existing, non-apple WiFi network and I want to use an Airport Express to be able to play music from my MacBook Pro (Mountain Lion) and iPhone (iOS 7) on the stereo.
The current WiFi router and the Airport Express can not be connected by a cable, so I need to use the existing WiFi connection.

To keep the cost down I want to buy a second hand Airport Express, but I noticed there are several versions.
Are all versions capable of achieving this? Or is one version better at this than the other?
Every express supports AirPlay. Some older hardware needs an older OS or utility to configure, so go for a newer model if you don't have an older PC or Mac (or VM) to run the old software to configure things.