When the findbar textbox has focus keys such as page up / down and home / end (others?) should affect content since these keys are not applicable to the findbar. After talking with mconnor about this he added that the findbar should auto-dismiss in this instance as well.
Home/end _do_ apply to the textbox and are needed when editing the search text in place. It could get quite frustrating if we rerouted these. And Up/Down and Page Up/Down already scroll as expected, don't they?
Just tried it and page up / down and arrow up / down don't work when find has focus with gmail when find is initiated and they continue to not work after dismissing the find bar with escape.