I just replied here with my motivations: https://github.com/soywiz/pspemu/issues/1
"D is just fine to create an emulator. The problem was that I was doing emergent design, so I was refactoring a lot. And design flaws caused the refactorings to be massive. D didn't had a good IDE allowing refactoring by that moment (not sure about that now). That was the main reason for me to change the technology. Also there was minor flaws: Compilation times were huge. I was using lot of compile-time code generation and at least at that time, that code was interpreted or not enought fast for me. Also I didn't get incremental compilation working, it failed everytime probably because that compilation-time stuff causing the compilation to take stuff like 1 entire minute. And that was unacceptable too for me. I needed to run it lots of times to doing research. Also I needed a needed to chaneg the emulator to perform dynamic recompilation instead of just interpreting. With C# I could do portable dynarec very easily. In the case of D I would have to creaet a emitter per supported platform (mostly x86, x64 and ARM).
And my decission to use C# was not because I didn't like D. In fact, I liked D a lot, that much that I started an emulator using it."
