Once years ago I did a side by side batch that I posted (on this forum or it may have been over on NB) of one hydrometer flask from a batch boiled with IM and one not boiled with IM from the exact same mash. The one with IM was clearer in the flask for sure. But still, I haven't noticed a difference in beers I want to get clear and fine in the fermenter or keg cold side. That said, it may help beers clear that are not fined cold side.