we really should say more clearly that this is really a windows-centric site. we always try to highlight open source cross-platform alternatives but the primary focus is on windows. you are right of course that serious ftp servers for large-scale stuff are often commandline tools running under linux. this was more of a focus on personal ftp servers rather than enterprise-class servers, or commandline unix/linux servers. i'm actually going to add that to the review now.
Serv-U is a very good product - i wouldn't set its easier to set up than blackmoon - they both strike me as about equal in that respect. The virtual directory thing in particular really gave us some trouble and is much easier to set up in blackmoon. also i kept leaving serv-u running by accident, wheras with i found blackmoon was less prone to that, due to better system tray integration, and didn't like the lack of built in better statistics/history information.
Several of the other servers could have won our recommendation - it was very close. Serv-u is an excellent program and you won't go wrong purchasing it. We just thought, for the reasons we gave, that in the end blackmoon slightly edged it out. But like we said in the review, for this kind of thing, you might want to identify the features most important to you and then look for the server that handles that best; many of them do certain things that the others don't and you might find one of those features is exactly what you want.