the tradeoff is mainly because you must force dimension limits, without a solution like i suggested....
that means you have to choose between limiting/resizing ALL member images to likely a much smaller size, and leaving the settings open... which, even if compressing, you will be serving 5000px images or such that are resized to view, but not in serving....so its the same basically as embedding multi 5000px images into a post..........sorry its not an easier answer, believe me i wish....i think the solution can depend how important/frequent image use is tho...