[Closed] how much seatpost is too much?

Depends on lots.

Obviously you need to be within the design limits of the fram and post (they're normally marked). After that it looks wrong if you've got too much and probably an indication of the wrong size bike. You are also going to bend long seatposts more easily.

Some frames have a minimum insertion, ie "Make sure the post goes below the top tube" or similiar. So watch for that... My problem with my Scandal was that with the 400mm post at full length, and the seat tube fairly slack with the 130mm forks, even with the seat mounted right forward on a zero-layback post I was still sat much too far back on the bike. So that might be a consideration too- my Soul gets on fine with almost as much seatpost, because the seat tube isn't so laid back.