In addition to the other suggestions, send a note to Facebook that you purchased their "FaceBook for iPad" app (include a link to the app store page) and are extremely disappointed with the functionality. After Facebook legal complains to Apple about the app perhaps the submitter will be banned and all their apps removed or at least their apps will be under much stricter scrutiny. And a request of your own to remove the "Pro" app may be better received. Also, contact the other devs who had their apps ripped off and urge them to complain about this submitter as well.
Good idea. The problem is "FaceBook for iPad" is listed in their submissions rather than in their apps, which means it hasn't been approved yet. However, if they end up passing the review (I have my doubts about that), I'll make sure to buy a copy and report back to Facebook.