i think people use more Bookmark Tool because it is cheaper. Of course Wiki is stronger and more powerful, but i saw myself as well using the bookmark tool to 99% and Wiki for just 1%. Myself not because of money reason, but much more becasue i got with Bookmark tool good results in the beginning so i was only keep on facing on that tool. I will shure use more the wiki tool, becasue i have some hard keywords and i want to see how that Wiki tool is now boosting the site. So now i can compare and see the time frame between Bookmark and Wiki.