dellus wrote

I vote for rounded line ends, definitely looks better, more natural and same as if drawn by real ink pens.
Maybe you will notice it on a real print out only with large pen widths. On screen of course you might zoom in very close and see it.

You said squared off line ends give better performance. How much is the difference?

Most other CAD's use rounded ends. In an older Nemetschek Allplan (architecture CAD) I have found pointed line ends. If QT can do this, maybe it's a compromise.