I didn't read the survey. I think it is pretty pointless to make such generalizations.
But I use a lot of open source tools and libraries, and they are good!
For me, the clincher is that, in most popular open source tools, you get a very fast response to requests for bug fixes or improvements.
For example, a few months ago, I found that there was no support for certain DOM objects in
HTML Unit, causing my tests to fail.
On enquiring about it, I got a very fast response. After a couple of emails, Marc Guillemot, one of the developers, added the required feature in CVS. It all took only a couple of days!
And if all else fails, you have the source code, so you can go ahead and make the changes yourself. It is good to have that option to fall back on.