I love the example you used--i have battled with the condensate drain system in my cramped crawlspace on numerous occasions... I had the misfortune of discovering it stopped working on at least 3 separate occasions, leading to standing water in the crawlspace until i figured out a way to get rid of the water and fix the problem. I've luckily come up with a solution each time (first 2 times was a clogged line, most recently it was a bad GFI outlet--curveball!) but i can't imagine how much I'd be paying other companies to get rid of the water and fix the problem each time. No doubt it's better than renting in certain respects but just like someone else here said--you can have a $20k problem happen, and you are the person responsible for putting up the $ or figuring it out yourself (which isn't always possible, or a good idea to attempt)...