Do eReaders Slow Down Reading?

Is reading print really faster than reading an eBook? According to the Nielsen Norman Group it is. The group recently did a test of usability on the iPad and the Kindle and found that reading speeds declined by 6.2% on the iPad and 10.7% on the Kindle compared to print.
But as CNN points out, the data is not significant. From CNN, “Nielsen conceded that the differences in reading speed between the two devices were not ‘statistically significant because of the data’s fairly high variability’ — in other words, the study did not prove that the iPad allowed for faster reading than the Kindle.”
The survey only tested 24 people. The report includes claims that iPads were too heavy and Kindles had poor contrast, but it lacks details about if these people are already reading on these eReaders. There is always a learning curve when trying out new technologies, so it should not be a surprise that people trying out iPads and Kindles for the first time might go a little bit slower that people reading books, a technology that has been around for more than a thousand years.
What do you think?