Using undocumented native code APIs to install items into the GAC

I'm working on a project whose setup uses the APIs documented in Microsoft Knowledge Base article KB317540 to install and uninstall assemblies into the GAC. The KB article states:

SUMMARY
The native code application
programming interfaces (APIs) that
allow you to interact with the Global
Assembly Cache (GAC) are not
documented in the .NET Framework
Software Development Kit (SDK)
documentation.

MORE INFORMATION
CAUTION: Do not use
these APIs in your application to
perform assembly binds or to test for
the presence of assemblies or other
run time, development, or design-time
operations. Only administrative tools
and setup programs must use these
APIs. If you use the GAC, this
directly exposes your application to
assembly binding fragility or may
cause your application to work
improperly on future versions of the
.NET Framework.

The GAC stores assemblies that are
shared across all applications on a
computer. The actual storage location
and structure of the GAC is not
documented and is subject to change in
future versions of the .NET Framework
and the Microsoft Windows operating
system.

The only supported method to access
assemblies in the GAC is through the
APIs that are documented in this
article.

Most applications do not have to use
these APIs because the assembly
binding is performed automatically by
the common language runtime. Only
custom setup programs or management
tools must use these APIs. Microsoft
Windows Installer has native support
for installing assemblies to the GAC.

For more information about assemblies
and the GAC, see the .NET Framework
SDK.

Use the GAC API in the following
scenarios: When you install an
assembly to the GAC. When you remove
an assembly from the GAC. When you
export an assembly from the GAC. When
you enumerate assemblies that are
available in the GAC. NOTE:
CoInitialize(Ex) must be called before
you use any of the functions and
interfaces that are described in this
specification.

What are the pros and cons of this technique? Are these APIs safe to use? Anyone out there using them? If so, why?