>I mean submitting sites that DO link to me - this does help with google.
Sumbitting sites that DO link to you does not really help in Google if the pages that you submit are isolated points in the web space with no links to them. If they have no links to them, they have no pagerank, and if they have no pagerank, they will not help to increase the pagerank of your pages. So, it does not really help to submit them.
If the pages that DO link to you DO have some pagerank, they could help you. But, if they have some pagerank it is because they are linked from some other pages. And, if they are linked from some other pages, Googlebot will sooner or later find them on its own. So, submitting them does not really help again.
Now back to Fast: fast lists also orphan pages with no links to them. So, if you submit a page Fast will include it in its algo. If the algo gives some extra points to your pages for every link, it would help you even if you submit an orphan page that links to you. But the algo does not work that way (my personal opinion).
If the algo had something similar to Google´s pagerank implemented, then only the linked pages would help, and Fast bot usually finds new linked pages rather quickly...
I mean :):I think it is not worth the effort.