I don't think there's a useful answer to this question: is open-source software support better than closed-source software support? While I believe that open source aligns vendor interests with customer interests, I don't think that this necessarily translates into world-class support. At the end of the day, people and process create excellent support organizations. Source code access is an important but not the defining factor in how good support is.
Mark frames his discussion around two graphics: one shows how support gets used in closed-source software (The X axis (vertical) is time spent on support and the Y axis (horizontal) is volume of incidents)...
This sounds about right to me, but it actually poses a quandary for those who make money from selling support subscriptions. Namely, if in the proprietary world one of the primary drivers of support is assistance during the installation process, and if you largely remove this in open source because people tend to get up and running with community support, has open source shot itself in the foot?
Sort of. In my experience, you still end up providing this support, either through your forums or your sales engineers (pre-sales support). You just don't get paid for it. What you do get from it, however, is early discovery of what prospects want to do with your software so that you can help them be successful.
In the proprietary world, the customers buy on hype and then, hundreds of thousands of dollars (or millions) into the snafu, they ring support to try to make the disaster less painful. In open source, they only engage support (through a paid contract) when they know the software is a good fit and they're ready to engage the company for advanced features, resolution of complex problems, etc. It's much better for the customer.
But for the vendor...? No, not as much. This is frankly why many of the open-source companies use proprietary extensions of their software in their business model. It's not because they think proprietary extensions help the customer, or because they have lingering affinity for the proprietary world. It's because they're trying to give the customer a convenient reason to purchase even when support won't trigger a purchase decision. It's not a model that I like, but it's one that I can understand.
All of which brings me back to the original question in the title of this entry. Is open-source support better? No, not necessarily. It does a better job of meeting customer needs with lower risk and lower prices, and allows them to more easily support themselves. As for whether the person on the other side of the call is competent and diligent to resolve the customer's issue, that differs from company to company, and project to project.
Just like in proprietary software.