If you're making 10 clones of an existing server you're still in the trade-off where spending a few hours now, deconstructing its setup and scripting it with Puppet/Chef/Juju/etc and setting up maintenance and monitoring is easily going to offset the time you would spend manually chasing around after servers running individual package updates and wondering what went wrong when a service drops off.

It's really boring sysop stuff... But as I say, it'll pay for itself within a couple of months and by the end of next year you'll either be thanking me for suggesting it or cursing yourself for ignoring it. IMO that applies when you're dealing with any more than two computers. It doesn't take that long to get this stuff set up.

But IP address and hostnames are the big two. If you're running network-provisioning services like a DHCP, that's going to cause issues but assuming these are clients, you're probably not going to see any more problems immediately.