Swaro - I have two z6i riflescopes - one on a .280 and one on a .260, both have done well for years - These were both handed down by a family member that no longer can hunt. He's done very well with his .280 and killing some mighty fine bucks. He didn't shoot the .260 much, I've played with it in the offseason, and it has held up well.
I run an old Zeiss Diavari on my main gun, 300 win. with a 56 objective.
OP, you are comparing a 50 to a 56 scope, low light is going to be better with the 56. That 50 should be lighter, however in terms of weight. The way to know is to buy both, don't mount either of them, take them into the field and see what they do for you and your eyes. Run them from the lowest setting, to about 4or 6 or 8 (that's about where you will hunt most of the time), very rarely, except at near dark, have I needed to turn mine up to 12. I've killed deer from short bow range to close to 500 yards over soy beans, now the longer shots I did have to turn it past 8, because I needed to see that hair. To let you know, I shoot at one particular hair on a shoulder, yes I shoot the high shoulder shot, I aim for one small particular hair, not the animal, not the shoulder, one exact spot. Send the scope that was your second choice back.
When you run the two scopes, if you can't see deer, pick out a tree limb and look at the smaller limbs, which scope lets you see those small twigs? When you turn it up to full power at very early or late light, which scope goes darker sooner? If most of your shots are within 150 yards, which most will be, which scope is brighter? Now, I don't worry about weight, the farthest I will probably walk is a 1/2 to 3/4 mile to a stand. You may need to be concerned about weight. Yeah, I've read a little about the swaro scopes, I haven't experienced it, nor have any friends that run them, so I don't know the particulars on it. I do know both scopes you are looking at are fine scopes according to others.
Now, let's talk about eye relief, how are your eyes? Some scopes have more than others, be mindful if that is a concern you may need.
