I know this is an old tool, but a few tweaks could make it very useful.
If SDM could be made aware of ip ranges and run as a service, any machine that gets connected to your network could then get the Netinstall client installed to them. Having a server running this sort of service at each location would prevent having the client files installed over wan links.
For those of you that use the inventory option, this would make sure you never miss a machine.
I know, login scripts can do this too, but this method provides an option for catching those stragglers that somehow fall through the cracks.