Nagios monitoring service is a brilliant example of open-source high quality software. Not to say, all open-source software are high quality, but one look at nagios and how it gives so many default monitoring, out of the box, and you see why it’s worth learning. Ofcourse, there are a million possible variations in the requirement of a Server Management and a million other services,hardware,metrics, but the beauty is they are all mostly configurable. I doubt any proprietary s/w team could support as much variety, by virtue of being a limited team size. (Pretty similar situation with Linux). On the downside, and yeah, i do think there’s a downside, this necessity of being able to support a wide variety, forces quite a lot of abstractions. the downside being, abstractions leak, slow down performance/speed(Look at Synthesis, Alexa Massilini). In the end, i would say that’s probably a dilemma any software made in the current world faces and makes some point of tradeoff. Which is better/worse, we can all speculate, but will be tested by time.