have both ,just bought a .45 since it was on sale. I checked the ballistics and here are both using a 240 grain bullet and 150 grains of pyro.

100 yds

.45= 0 drop , 1945ft sec , 2016 ft lbs

.50= 0 drop , 1671ft sec , 1488 ft lbs

200 yds

.45= -7.72 drop , 1735ft sec , 1605 ft lbs

.50= -11 drop , 1491ft sec , 1185 ft lbs

Seems you gain a wider variety of accesories and .05 of bullet diameter with the .50 , the ballistic data says go for the .45. Havent gotten a scope for my new .45 yet , so we'll see how she shoots when I do. Keep ya posted