For your ordinary average everyday normal well-supported language, stick with the IDE.
But suppose you're working with some random language that nobody's ever heard of. It's some tool-, product- or site-specific thing. If you're very lucky, there's some ropey Scintilla-based text edit widget that lets you work with one file at a time. If you're not, there's quite literally fuck all. When you search on Google, there's 0 useful results (until you get to page 9, and there's 1 single post from somebody, on some random forum for general blarney, ranting about how they're doing some contract work and using this stupid language and it's terrible because there's no tools and they're stuck using notepad and their life sucks).
If you've got an IDE, now you're sort of stuck. Maybe you can find a language it supports that's a bit like, and then you've got syntax highlighting - sort of - and autoindent - maybe. But you have to do code browsing by grep, effectively, and you've got 0 in the way of code completion.
With emacs on the other hand you can relatively easily code up some language-specific support for syntax highlighting (takes 5 minutes) and autoindent (5 minutes for something basic, maybe 1-2 hours if you want to get fancy). Add some imenu regexps (5 minutes) and you've got code browsing from within a file. Put your imenu regexps into Exuberant Ctags (15 minutes), and you've got cross-file code browsing. Code completion... well... yeah... it's not perfect, but if you squint a bit, dabbrev (2 minutes if you need to tweak your syntax categories) is fine.
I've never failed to turn a time/effort/hassle profit from doing this.
But suppose you're working with some random language that nobody's ever heard of. It's some tool-, product- or site-specific thing. If you're very lucky, there's some ropey Scintilla-based text edit widget that lets you work with one file at a time. If you're not, there's quite literally fuck all. When you search on Google, there's 0 useful results (until you get to page 9, and there's 1 single post from somebody, on some random forum for general blarney, ranting about how they're doing some contract work and using this stupid language and it's terrible because there's no tools and they're stuck using notepad and their life sucks).
If you've got an IDE, now you're sort of stuck. Maybe you can find a language it supports that's a bit like, and then you've got syntax highlighting - sort of - and autoindent - maybe. But you have to do code browsing by grep, effectively, and you've got 0 in the way of code completion.
With emacs on the other hand you can relatively easily code up some language-specific support for syntax highlighting (takes 5 minutes) and autoindent (5 minutes for something basic, maybe 1-2 hours if you want to get fancy). Add some imenu regexps (5 minutes) and you've got code browsing from within a file. Put your imenu regexps into Exuberant Ctags (15 minutes), and you've got cross-file code browsing. Code completion... well... yeah... it's not perfect, but if you squint a bit, dabbrev (2 minutes if you need to tweak your syntax categories) is fine.
I've never failed to turn a time/effort/hassle profit from doing this.