I agree with pretty much all of his points. But the argument that code will 'never align' with line numbers seems like a dismissal that debugging exactly what you wrote is very valuable when tracking down subtle bugs.
Fair enough. I don't need line numbers specifically when I have a full-on in-browser graphical debugger so I can debug exactly what is being interpreted. There's work underway to handle mapping back to source files, and when that arrives, it will be "nice". However, listening to NodeUp podcasts, people think that line numbers not lining up is an absolute deal-breaker, which I just don't find to be the case at all in my personal experience.
I also think that lack of line-number mappings is a fair criticism of coffeescript. If the article is rejecting FUD, then it should target statements like "debugging is a nightmare." I agree with the author's overall point that you can usually track down problems without a lot of fuss.
Or not-so-subtle ones, debugging Cocoa is a pain even for simple stuff (such as the wrong format spec to NSLog) when Xcode drops you into a debugger full of assembly 9 times out of 10 instead of saying "Look here, this NSLog call makes no sense" and dropping you in obj-c code.
