On my first trip to Zim, an elephant hunt, I was separated from my rifle and duffle for the first 2 days. The outfitter lent me his SS Rem M-700 in 416 Rem with a Leupold 3-9x scope on it. I carried it reluctantly until my rifle caught up.
On my next trip, I found out that was his lending gun. He carried an open sighted Win M-70 CRF 458 Lott. This time I had no trouble, my DR 500 NE 3" made it with me all the way to camp. I like 416s, both the Rem and Rigby variants, but prefer 404s. No rational advantage I can see to either, just a matter of personal preference.
BTW, my favorite use of the RSM 416 Rigby is converting it to 450 Rigby Rimless Mag. Did that with one I intend to take to Africa next year as part of my revised 2-rifle battery, although my second RSM remains an unmodified 416 Rigby, a nod to tradition. More rifle lunacy
