Performance wise they are closer than many think. I've owned 41's in the past and have 44's now just because it makes life simpler. I'd not feel at all undergunned with a 41 instead.
Theoretical advantges are
Slighty reduced recoil
Slightly flatter trajectory
More beef in cylinder walls to make a stronger cylinder.
Whether those really help is debateable.
To me you choose a 41 mag for the same reason you choose a 280, 35 Whelen, or most any other odd ball chambering. You get to use something different from the masses without really giving up any performance. You don't really gain anything either.