Those are the models I compared when I purchased. I currently had a 44mm in the VX5HD and wanted another. Wound up purchasing the 56mm(same magnification). I literally cannot tell a difference in brightness in low light. The 56mm sits on an AR-10. The mount was pretty high allowing a larger objective so I filled that gap up but there is no difference in the amount of light I gain with either model.I have this in the 3-15x56. It’s a great scope. Not a huge fan of the 56 but I originally thought it would make things better in low light conditions over the VX5HD with the 44. Leupold said not really. It’d be so minuscule that your eyes probably won’t notice. But the weight difference between the 2 sizes isn’t that much. So depending on your needs go with either one and you won’t be disappointed. But the 56 is harder to squeeze into some cases as one of the other guys mentioned. I ended up buying a larger case just so it would work better.