Thanks for the info. As long as my Digitrax with wifi TCS throttles works, I won't need to go the DCC++EX direction but always good to know should the need arise.
If you want the Raspberry Pi to connect to your existing WiFi network (for communicating with WiFi throttles/apps, etc.) then you will have to log into the R-Pi and make some simple changes to a text configuration file. The instructions are available on the website for the SD card image. I use a free VNC app on my laptop to remotely access the R-Pi's desktop GUI whenever needed. It is easiest if you can (temporarily) plug your R-Pi into your router's ethernet port, since after you configure the R-Pi to connect to your existing WiFi network, it no longer provides it's own WiFi network, and you need a way to log in and give it the network access credentials (Network ID and password). After that, the R-Pi will automatically connect to your WiFi every time it starts up. I use VNC (from my laptop) when I am programming decoders using JMRI Decoder Pro. Compared to programming decoders via a throttle, DP is, well..., there is no comparison! DP is MUCH better in EVERY WAY!!! Also, when you give a descriptive name to your loco's entry in DP (it remembers what your decoders' programmed settings), then WiFi throttles/apps give you a list of those names to select from, to control from the throttle. While JMRI is configured to start the Wi Throttle server automatically, which broadcasts it's location (so throttle apps don't have to know the server's IP address), re-connecting via VNC requires knowing the R-Pi's IP address. You probably want to configure your router to assign the same IP address to your R-Pi every time it connects. On some routers, this is referred to "reserving" the R-Pi's current address, but the routers all have their own different user interfaces for configuration. The Pi-SPROG 3's provided Pi SD card image is very similar, if not identical, to Steve Todd's image.
