I don’t want to pick on details, but you say “- lowering the bid may result in a lower ad position which may lead to less clicks and therefore a lower overall ROI”. I don’t think that’s correct, because if they don’t click, you don’t spend money. In other words: if there’s no investment, you can’t get a good return on it.

So if you lower your bids, there might be less visitors. However the visitors on your site will have cost less in advertising, so it’s really a thin line.