Some people have gotten the impression that Quick Render is different, perhaps even somehow more "stable" than Full Render. They are both basic Render Nodes, which you can create like any other node, so there is really no difference between them except for detail settings. Thus the Quick Render has lower detail and renders faster and the Full Render has higher quality, rendering slower. If either one seems to work better for you it's certainly just down to the settings used. Most of the difference comes down to the basic Detail slider, the Antialiasing, Global Illumination quality, and render resolution.
In general it's useful to be able to have multiple render nodes with different settings as it allows you to switch settings quite quickly and easily and do some cool, more complex things as well. I agree however that being able to sync some settings between nodes would be nice.
- Oshyan