Customers prefer to speak to a real person instead of a speech IVR: we in the speech industry have heard it said a million times, and never with any data to back it up. Now, there's a survey that claims Australians prefer to speak to IVRs than to CSRs in overseas call centers.
Now, the first thing I want to know when I read about a survey is the methodology used, the questions asked, and the see the real data. This CNET article that I linked to doesn't give specifics, and the published report is very expensive, so I can't vouch for the quality of the research. I'm quite sure that the survey respondents were thinking of efficient, well-designed IVRs, since there's almost nothing so aggravating than a malfunctioning IVR. But, if the generalization that a group of English-speaking callers prefer speech IVRs to overseas CSRs, then there exists data that partially refutes the argument that customers always prefer to speak to a live CSR.
Personally, I always take a shot at using self service on the phone, since I never know how long I'll be waiting in queue before talking to a person. Maybe it's just professional curiosity, but I like seeing how different IVRs operate. And if the IVR can't give me what I want, I haven't lost anything. I'm assuming that a lot of people feel the same way, but I don't have any data. The CNET article is a pointer to some real research that should be replicated in the US and elsewhere.