44 40 vs 45 Colt in a Single Action Army: Which would you choose?

Originally chamber in .45 Colt, the Colt Single Action Army revolver could be purchased in .44-40 by 1877. This allowed customers the convenience of carrying the same ammunition for both their Colt SAA and their 1873 Winchester. It wasn't the first time in history this convenience was available, but it was certainly a marketable and appealing offering. Was there a downside or sacrifice for the sake of convenience? Let's test two loads with 40 grains of black powder and find out if one cartridge outperforms the other.