Yeah, the Duo sounds like it's going to be pretty great. With the way the custom firmware has worked out on other Analogue systems, it is possible that other CD systems might be possible to run on the Duo as well with future custom firmware. Likely just in the 32-bit generation range, but it is still interesting to think about.
For anyone looking to get some compatible controllers for these legacy systems, I encourage the 8bitdo 2.4 Ghz model controllers. They are very affordably priced, perform well, feel good, and usually look close to what the original models did as well. If you want a bit more flexibility, you can instead get the 8bitdo bluetooth adapters. They work as well, and provide a lot more options for connecting. They will provide more expense, though, as they typically go for around $20 each, and also require you to purchase a bluetooth controller on top of that. They are a particularly good option for anyone who already has 8bitdo bluetooth controllers, as they work with all of them.
When I got my Mega SG, I ordered a pair of matching white 8bitdo 2.4 Ghz controllers to go with it. The whole set is just gorgeous, and performs very well.
Tbh krikkz genesis controller is better