I also think "more screen space" == "more productivity" is a fallacy. There was an article here the other day where someone used a Surface Go as his primary development machine. That's a bit extreme, but I used a plain 15-inch MBP without a second monitor for several years at work and didn't feel hindered whatsoever. Of course it depends on your workflow; game developers or film editors tend to need more things onscreen at once, for example. But I think programmers get too excited about more/bigger monitors because they look cool on a desk and are relatively inexpensive these days. And they, you know, feel productive.