Why would it be any harder for them to use FreeBSD than Linux? BSD has pretty much almost all the same apps as Linux. Which one is harder is who you ask. Some may find BSD easier to use since it's more consolidated.
I don't use BSD so I don't know for sure, but iirc, FreeBSD has gnome, KDE, Xfree86/Xorg (take your pick), and pretty much all the rest of the main stuff that any Linux distro does. It of course has some of it's own stuff as well. I believe it also runs alot of the same GNU programs/applications and utils, but some of them are replaced by BSD centric variants instead.
It sounds like you're coming from the mindset that BSD is only good for servers and not for desktops. I believe that is a common misnomer about it much like a reflection of the common misnomers about Linux. My understanding is that it's as much suitable for desktops and workstations as Linux is. I just think that it tends to get alot of kudo for being a great server platform because of it's different development model that tends to be more ideal for maximal server security and performance. But I believe, just like Linux, it's a versatile OS that can be applied very well to many different needs and tasks.
Unix type OSes tend to be terse in general. There are of course some distros that cater to more hand holding and user friendliness, but if those facilities fail to get the job done, then you're back to having to do things the "hard" way. Except it usually seems the "friendlier" distro actually end up being more difficult to get working right in those situations since there tends to be alot more abstraction going on.
If I were you, I would base the decision of what to install on their systems based upon what you are most comfortable with and what supports their hardware the best, both in terms in deciding between BSD vs. Linux and distro vs. distro.
You ask people what distro you should put in their systems and everyone is going to have a different answer. Alot of that is going to be based upon what they've experienced with the hardware they happen to be running and may not end up being the best route to go in your particular situation.
Here's a little link that may help you with making a decision. I like this link because it looks at things from a fairly objective standpoint. However, you can tell that the author is a fan of FreeBSD and it is his preference, but he does a good job of explaining some of the differences between Linux and BSD and what the ramifications are.
http://www.over-yonder.net/~fullermd...bsd4linux2.php
LOL, it's kind of funny how I am a Linux user and sound pro BSD in this thread, and you're a BSD user sounding pro Linux. Gotta love it. I guess it's testiment to how good they both are.
Like that one guy in here told you. You're in the best position to make the call.