Occasionally I've stumbled on conversion output where every sentence is a new paragraph, not whole books, normally short passages. Or where several paragraphs get joined into a Proustian screed. Having the original and a 'no line-wrap' editor makes it easier to reconstruct the original paragraph structure.
That Sigil doesn't have a no-line-wrap toggle has never bothered me, there are zilllions of editors that do - even Notepad has it
I just don't get the attitude that every tool must have every flying fish and duck that the gods ever invented to put on wall - I can't saw wood with my croquet mallet either
Open With is the best gizmo anyone ever added to Sigil.
BR