I am a huge fan of PingPlotter, it's been super helpful in monitoring key devices on my network.
I'm wondering if it would be worth monitoring almost all of the devices? We're a small/medium sized business, I'd have about 20-40 devices per location, with four locations total. I probably wouldn't setup every single PC, but all printers and some multi-user workstations, and some equipment at our manufacturing plant would be useful to get on pingplotter. Especially with alerting for some devices.
I understand this is relative to the environment, but is there a "rule of thumb" for when monitoring starts to affect performance?