I've used quick fists in the past without issue. To the OP I don't see them having a problem especially since you have your tools laying flat on your rack, so there is no weight that the quickfists need to hold. They only need to keep them on the rack. Mine were holding the tools vertically and had to support the weight of the tools and I didn't have any problems with them for almost 5 years of use.
Maxtrax mount by
Adam Tolman, on Flickr
But the "anti-rattle" bracket from DeltaVS is an awesome piece to keep your tools where you want them. I have since swapped out my quick fists for the Delta bracket.
Untitled by
Adam Tolman, on Flickr
Untitled by
Adam Tolman, on Flickr