Informal poll on reliability of AIO liquid coolers

TL;DR: Have you ever had or heard of an AIO liquid cooler leaking? What happened afterwards?

The long story:
This morning I received a NZXT Kraken X41 from Newegg. It was intended for a build I'm working on. While unboxing it and eyeballing the position of the radiator in the case, I noticed a bit of wetness on my hand. I first discounted it, since the device was still icy cold from being in the delivery truck. Then I noticed it was real liquid.

Careful inspection showed a small leak where the hose enters the radiator reservoir.

Newegg (I'm a Newegg Premium member) was incredibly helpful in arranging a speedy RMA and the replacement is already on its way. However, the person I'm building this rig for is now very apprehensive about future leaks.

I myself have only ever had positive experiences with AIO coolers. All desktop computers in my household, as well as the vast majority I've built and designed have AIO coolers. Depending on circumstances, I choose between the Intel-branded AOI cooler and NZXT Kraken. I once installed a COrsair H50 (or ZH55 - I don't recall) but didn't like it much an had to replace the fan to get it a little quieter.

So now my question. Until this morning I would have given huge odds that AIO liquid coolers are highly reliable and extremely unlikely to spring a leak - about as likely as RAM stick are to be DOA. Now I'm not sure and I'm asking Tom's Hardware community to share their experiences. Either help me build up my confidence, or tell me your horror story and how it was handled by Customer Support of the manufacturer.
 
I have never had an issue (other than acoustics) with an AIO cooler.
Leaks are possible, but not common.

This is more of an issue of QC than reliability. The unit was damaged (or already damaged/not properly sealed) in transit, not in use. I would pin this more so on the manufacturer than reliability.
However, no matter what there will always be people who dont want water in a system.