>But we don't have a ton of empirical evidence on our side
Neither does the other side, unless you accept the premise that reading natural language text is similar enough to reading heavily indented code where that indentation has meaning. I don't accept that at all.
The studies that were done on natural language text assume that line length is equal to the column where the line ends (i.e all lines begin on the left edge). That's not usually the case for indented code.
If reading long lines takes more effort because your eyes have to travel further to find the next line, then the amount of indentation the next line has matters are great deal.
My point was that there is no writing that extends to long lines. If anything, the fact that no other writing form has made such extensive use of indentation is enough to give me pause and think if that is making any sense. (I do note the amusing lines in the Linux style guide on the use of heavy indentation.)
And looking at this before I hit go. You seem to ultimate be agreeing. Taking opening indentation into consideration concedes that long lines are bad. You just give some room for margins. And are ok with all of the mental stacking that the indentation implies.
Neither does the other side, unless you accept the premise that reading natural language text is similar enough to reading heavily indented code where that indentation has meaning. I don't accept that at all.
The studies that were done on natural language text assume that line length is equal to the column where the line ends (i.e all lines begin on the left edge). That's not usually the case for indented code.
If reading long lines takes more effort because your eyes have to travel further to find the next line, then the amount of indentation the next line has matters are great deal.