When the puzzles are scored after closing, I think another thing that should be taken into account is how long a player worked on a puzzle. Players with very high final ranks who began the puzzle much later than others folders deserve some sort of bonus. I've seen (and had) multiple top-30 finishes on puzzles that were started 3 or 4 days after they opened.

Of course, this would not work with evolver puzzles, just solo.