Didn't know about the Quick Find functionality.....
Been there longer than I can remember, since version 1 or before, IIRC. They call it 'Find As You Type'.
... but where is the Next/Prev functionality?
F3 for forward, Shift-F3 for backwards, Ctrl-Z to clear.
The way I look at it is, I've already got my hands on the keyboard - I don't want to keep reaching for a mouse just to push a button.
Not to mention if you pause to think too long the Quick Find box goes away.
But the last search is still in effect, you hit (Shift)F3 and it will find the next/last occurance.
I think you can change the timeout but I've always found it faster to just start typing what I'm looking for, (you can turn off the requirement for hitting '/' first: Tools->Options->Advanced->Start searching when I type). Plus I prefer the uncluttered look of not having a Find bar there.
I don't think I've ever used Ctrl-F to initiate a search, actually I don't think I've used Shift-F3 to search backwards either - it was easier to hold down F3 and let it cycle around Addendum:
For some typeahead parameters that you can modify in about:config see here: about:config Category:Preferences
for the following Accessibility.typeaheadfind.[parameter]
Take heed of the warning if you do choose to use about:config.