Whoever said that doesn't know what they are talking about.

Its decent. But way over priced for what you get. I guess its simple
and anyone can figure it out, but if your a filemaker developer you
should be able to figure out configuring RDP or VNC; its hardly rocket
science.

Start with:
http://www.filemaker.com/downloads/documentation/fm8_security.pdf

A 'remote desktop' solultion (a la gotomypc) is preferable
securitywise because only the screen data crosses the network not all
the actual the database traffic, it also has the benefit of being
faster in most cases.

However a properly setup VPN is fine from a security point of view.

The secure connections feature of FM server are also to my knowledge
fine, although I wouldn't rely solely on this over a WAN link because
it DOES mean your FM server can be attacked directly from the internet
and makes it vulnerable to denial of service and other attacks, even
if they can't get your data, they can disrupt your server potentially.
So you have to weight that risk. If you use a VPN, the worst they can
do is bring down your VPN server.

If I were exposing 5003 to the internet, I'd at the very least enable
encryption and set up a firewall to restrict the range of ip addresses
that it would accept connections from to a whitelist.

Of course it really depends on how paranoid you are, and how valuable
your data is, and what the impact of a security breach would be, to
assess how many layers and what kind of security you need.

-Dave