Island,
You really need to use ML a lot, and get to know it inside and out to understand all of its quirks. If you do your homework (and unfortunately the majority of people don't), you can absolutely use it reliably on pro shoots.
On my last film shoot, we had perhaps the most reliable and smooth experience with ML on a 5D3. No corruption whatsoever, no weird black levels. Everything was solid and the audio syncs perfectly.
We had a couple of small issues on set. One of the CF cards started acting a bit funny and dropping frames about halfway through the shoot. I suspect the camera was running very hot and the card was affected by the temperature because when I got it home everything worked perfectly again. The 3 other CF cards did well through the entire shoot without problems.
The key is knowledge and preparation (and a DIT that really understands the format and knows how to check it and process it). It's not a plug-and-play system, it requires dedication to it, but if you're willing to roll up your sleeves and do your homework, it can absolutely be a very reliable and stable way to capture footage.
P.S.
I would also point out that high end cameras (particularly RED) are prone to failures in the field. Here's an oldie but goodie that will make your skin crawl: