IDE vs Editor and terminal for CS1

TL;DR Those two aren't your only options.

The main concern is cognitive load: learning to program is difficult enough without adding incidental complexity.

We've seen an explosion of hybrids in the last few years with good cross-platform support: Sublime, Atom, VSCode, etc. And while you couldn't pry vim out of my cold dead hands, learning it is easy if you already know programming but would be a nightmare if you had to learn it and programming at the same time. Ditto for emacs.

And that also applies to IDEs like Eclipse and Visual Studio. They have their own way of doing things. They take forever to open. They are user configurable but not easily. I'll never forget the first time I opened XCode and basically said "what the hell is all of this?"

Have your students download atom which works reasonably well out of the box with a healthy plug-in community for growth. It's scriptable in JavaScript and themeable with CSS. Unlike notepad it gives you features you actually need to program, unlike nano it uses standard keyboard shortcuts they'll already know from e.g. MS Word (Ctrl-C, Ctrl-V, Ctrl-S, etc). And unlike VS/Xcode/Eclipse it doesn't obscure what you're doing: editing text files.

Edit

Can't believe I forgot to mention this but...

They more or less made us use Komodo Edit (free version of the Komodo 'IDE') in my first programming class, which is exactly the kind of thing I'm talking about and I think it really helped. Simple, no configuration necessary, things that should be easy were easy, etc. Don't know if they still offer it or not but I'd say Atom or VSCode arn better along just about every conceivable metric.