About a year ago I wanted to replace newlines in a file with "sed" on FreeBSD. I couldn't.
At first I thought there was an error on my side. I was very surprised to find out that you could not do that at all, it said so right there in "man sed".
Dirty hacks to work around this problem posted on stackoverflow did not work on that machine either.
Tried to mess with newlines with python. Turned out there was some kind of other problem if you open files in 'wb' mode under FreeBSD.
This experience with some of the most basic tools not working as they do on GNU/Linux made me want to avoid FreeBSD if possible.