I was planning on approaching people in the same niche as me with similar websites and asking them to place a link in the footer of every page on their website back to my site. In return i would do the same. I was planning on doing this with say 5 or 6 high quality sites that would agree to it (my site is also high quality with lots of good content). All links would be ********. Is this likely to improve my rankings in the SERP's? What are peoples opinions of such a practice, do you find that the websites just remove your link after a while and don't tell you? Is this a good idea or a bad idea?