This tool only checks the first three pages because people rarely look past the third page in search results. Do you? I rarely get off page 1 and 2. Anyway, you can use our Google dance tool to see where your site is on google, You can select from 10 to 100 results, then click "next" to look through as many results as you wish. But it is only Google and 5 of thier data centers, but it will show if your site is rising or dropping in their SERP's.
Here it is: http://www.searchbliss.com/google-dance-tool.htm
Too true, I rarely go beyond page 1 or 2 so obviously that is where I want my site to be and at present it isn't, I'm just trying to find where I am with different keywords because the idea was to look into the worst placed one first