Me I use the FS on defense and my pass defense is pretty good. If I was playing against big time TE I would use Cover 1 to let an athletic safety cover him then me being the FS in Zone for Cover 1 could double him.
Of course if your corners aren't good enuff to be left on an island you may struggle with this idea.
I found that it's almost harder to cover a big time TE than it is a Big Time WR becuase the best TE routes for the most part are all at one position. Whereas the best WR routes in different formations could be the slot or flank or elsewhere.