firstly, yes - the forum search engine works just fine, what matters mostly is what words to search on. try 'four inch feather' and not '4" feather'.
second, asking questions yields opinions that may be good for starters but the rubber will meet the road when you do your personal homework.
so, fletch up some shafts with 4" feathers and see for yourself if that will work with your form, your bow, your kinda bowhunting.
if you chop or burn fletchings, try different shapes and different feather heights, and by all means do try a 4" four fletch.