I'm really surprised that binary CNNs aren't more popular - i understand that you're taking a decent hit in performance for CPU usage & a GPU really isn't all that expensive - but to me it's really interesting. When XNOR came on the scene in 2016 i thought they were really going to shake up deep learning and we'd see more binary CNNs pushed by Intel & AMD to counter the dominance of NVIDIA, but it never really happened.