I own examples of both the 457, an early blue version, and a 4516-3, late post official end of production LEO pistol.
My 457 gets carried more than the 4516-3. Lazyness on my part being the only reason. I can carry the 457 IWB without a gunbelt. My 4516-3 requires a reinforced gunbelt for comfortable secure carry.
Both are reliable, accurate, and similar in size. Be advised that while all 457 holsters will work with a 4516, the reverse is not always true. Especially form fitted holsters.
I'll tell you what, the S&W 45 pistol I like to carry most, is my 4563TSW with the stupid rail removed, and a spurless hammer installed. It just carry's great, IWB or OWB. Extra rounds over both my 457 and 4516-3 too. Just my 0.02. All are great 45's. Pick what works best for you. Good luck! Regards 18DAI.