I was so use to the 80's game and its crazy difficulty that maybe i wasn't the best one to test this game :)
About C#, the most tricky part is to set up an external editor (i use Visual Studio Code ) for auto-complete and debug. I can't tell if GDscript o C# has better performance (i'm sure there is a lot of articles about it), but i don't have much free time, and i have been working with C# for a decade, so i feel more confortable and fast working with it.