There is no 1000 sub restriction for fan finder. It just takes longer for the fan finder to start showing your video if you have less than 1000 subs. That rumor is what happens when people who can't understand basic english jump to conclusions that YouTube is trying to screw them.
The fan finder ad works primarily upon the results. So if you aren't getting good results from it, it's because the watch time from the ad sucks. So if you see poor results and horrible watch time, don't expect YouTube to show your video very often-and since you're allowed to upload multiple videos for Fan Finder use, keep rotating in better performing videos if you want your ad to be seen.