Short answer; if you're asking on Slashdot for reasons to switch from product X to product Y, you probably have no real reason to switch.
The long answer was pretty good, but I disagree with the short one. Asking a (presumably) knowledgeable group of people questions like this is a good way to get a more complete picture of the problem space, and asking people from other companies might just score him a few stories about what worked for them and what didn't work.
Here's an anecdote from me: back when I was a fresh-faced, naive junior engineer I wanted to sell management on an open source alternative to an expensive commercial package by targeting some low-hanging fruit and arguing that we should use both. I surveyed my colleagues and found a number of small items here and there that could be automatically ported to the open source version, and demonstrated it to my manager. It wasn't good enough, because there were no hard numbers on what the company might save by doing this.
In other words, as you say, he needs clear financial benefits. Your Mileage May Vary, but these days I would not be surprised if, to his management, the financial justification is far more important than the technical justification.