Benchmarks speak louder than anecdotes. The article is a couple of years old, but clearly shows the differences in scalability for several OSes, including the two *BSDs you are looking at. The code is provided, so you can re-run the tests on current versions if you wish.
For the lazy, OpenBSD did not scale well to high volumes of web traffic.
The intelligent reader will judge for himself. Without examining the facts fully and fairly, there is no way of knowing whether vox populi is really vox dei, or merely vox asinorum. — Cyrus H. Gordon