After getting weird results with that too (faces completely deleted) I decided to have a look at the test scene in the help file.
In that scene the node worked just fine, so i copy pasted it into my scene and lo and behold it did exactly what i wanted! Afterwards I noticed the one I had been using was Dissolve2.0 and the other one is a 'hidden' older one that you need to switch to, it's not in the menu.
I just wanted to say should the new one work the same? If so how do i get that result in the screenshot. And hopefully there's no plans to delete the old one because it seems to work ... dare I say ... better?