To answer your questions, I was planning on using their latest 3.3 Stable release. For the # of devices, I want to leave room for scalability for testing in my own environment as I add more VM/pcs/servers, etc. At first, I plan to add the 3 Hak5 devices I bought over the years, but plan to buy different equipment for different testing like network exfiltration, keystrokes, Wifi pen-testing etc. Currently, I do not expect to run many tests concurrently, so I do not think the amount of data extracted will be too over the top. I expect this to change in time as I learn more. Think in the range like running the LAN turtle on one pc.
My original plan was to start this on an SBC like the Pi 3 A+ if the mins are not too demanding; however, over time as my lab grows and the # of machines grow, I was thinking of dedicating a mini pc with 4 cores 8-16 GB RAM max to it. Do you think this would be too much assuming a 20-30 max device setup or am I over/underestimating the resource requirements for the c2 server?