The complaints seem to come from people who use it too aggressively, if you do decide to use it make sure you search around here for settings that dont attract a lot of attention from twitter. Keep in mind that frequency is a big issue with them so if you task it to work quickly, you'll have issues almost immediately. A good guideline is if it does things you cant do by hand, then twitter will know it. I dont use FL regularly now, but with massfollow ( free- did i mention free?) i put in a 4000ms pause between follows. Unfollows dont appear to be watched as much, but i still have an 1100ms pause there too just to be safe. Also dont do your follow/unfollows in the same 24hrs. If you lose a day because of going slower, suck it up and deal with it: slow beats dead.