Yes, because of the extra reach and quick focus. If you are using it on a crop camera YOU NEED THE EXTRA REACH. This king fisher shot was taken by my wife on a D850 (that crops at 20mps just like the D500)and a Tamron 600 G2 lens. Have you ever seen any other GOOD kingfishers in flight shots on here? Both of these shots were heavily cropped and we wouldn't have gotten them without the extra reach.
Do you use the Tap-in and the custom focus limiter options? I believe with the Tamron you need to reset one of the existing positions while the Sigma has separate customization switches for the optional limit options.