If I understand your patch correct, it would change the default behaviour to do exactly that what my PL does, but per default and without a hidden preference.
Correct.
...but I think a hidden preference may be better than changing the default behaviour without allowing users to fall back to the old default behaviour.
IMO, a preference is not needed here and was only suggested as a result of a misunderstanding of the desired behaviour. Perhaps I'm missing the use case for _not_ wanting the search text to be updated. If the reason to jump back to the Find dialogs without updating the text is to click the Find Next/Previous buttons, then one can simply use the keybindings for this (<kbd>Ctrl</kbd>+<kbd>g</kbd> and <kbd>Ctrl</kbd>+<kbd>Shift</kbd>+<kbd>g</kbd> by default). If the reason is to jump back and change some of the options without updating the search text, one can simply press <kbd>Ctrl</kbd>+<kbd>f</kbd> followed by <kbd>Up</kbd> to recall the previous search string before changing the other options.
Is there another use case I'm missing?