Tunnel IPX Through IP

I've tried unsuccessfully to set up a VPN between three separate office
locations with BorderManager. However, I figured out a way of creating an
IP tunnel (using INETCFG) to establish communcation between the servers at
two locations.

We don't have users trying to access our servers from outside the office,
we only what the servers to communicate (and for eDirectory to stay in
sync of course).

Are there any disadvantages to using the IP tunnel instead of
BorderManager? I'm especially concerned about security risks. Thanks.