Other thoughts... If your thinking is to use DCC EX as the base and JMRI-PI as CS but concerned about which Pi and its present costs and/or extra hardware, I'd get started with the Mega, motor shield and wifi shield or ESP8266 module and adapter. Install Arduino IDE on your current PC and play around with EX. If you find sufficient a pc can be used for JMRI decoder pro. If not get a Pi or laptop and the most your out is the wifi card, about $10-15 USD as wi-server and wifi services will be handled by the JMRI-Pi(or PC). I own an iPhone 8 which, for my old eyes, screen is just plain too small. Spent $50 on a 8" F-Tablet where ED boots and automatically connects, freeing my phone for other things. Running ED on the larger tablet has pretty much dismissed the need for a physical throttle. Another plus is that with a Bluetooth connected mouse on the tablet, the screen is large enough to VNC or remote into the Pi and make simple changes in JMRI or write a basic decoder CV, if inconvenient to connect using other means. Agree totally with @BigJake as a good approach too! Especially if you have family members or other devices that are already connected to your network and you wish to control trains from. The SD card copier is a great feature for an image backup and if using Todd's Pi's image with the SMB shares, most of the user configurable files are located in one of the 2 shares, eg panel files, locos files, enabling fairly easy way to backup individual configuration from the Pi to another device or flash drive. My Pi 4b is mounted underneath layout and do not want to use a laptop or another large device to run the layout. My recent DCC EX exploration was also to see whether DCC EX and Arduino alone can eliminate the Pi or a pc JMRI for OPS running (Nothing beats JMRI for programming locos). Fewer parts, lower cost, higher reliability, lower power consumption, lighter are primary factors for my layouts so the elimination of the Pi if possible, will be done. As the saying... Its your railroad.. Decide on what's important within the budget. Think a case can be made to go pure DCC EX or JMRI-Pi. There is a lot of work going on at DCC EX and part with the upcoming EX Turntable (currently in Beta) so DCC EX with additional hardware, like other systems as mentioned earlier by @Sumner, can do auto-reversing. Other observations....Adding locos to roster and pushing out throttle labels, JMRI wins easily. Turnout setup, think is a toss up. DCC EX offers 3 ways to control turnouts-solenoid, servo and vPin. Scenery lighting & automation EX wins... Hardware customization-using Arduino DCC EX HAL is sweet. Support DCC EX the best! Personally think backing up DCC EX is easier. Highly suggest looking at DCC EX EX RAIL, the command set for automations, routes and sequences and also handling tasks such as turnout control & signaling. The biggest drawbacks to DCC EX is coding, making updates and pushing them out. Also, JMRI has been around a long time whereas believe DCC EX is early 2020. Just wanted to share some of the really cool things that DCC EX can do.