The european line use 0.5cm at 100m click. This is equivalent to 0.05mills as used by the military but of no use in hunting as once adjusted you do not play with them for drop correction !
The main difference is the so called German reticle that has thicker posts.
They are easier to see in low light, especially on wild boar.
Still hunting is autorised one hour before sunrise and one hour after sunset and in some places during the night mainly for wild boar and fox.
Variable european scope have also the reticle that changes with magnification, that means the reticle is thicker at high magnification, thus improving its visibility usually at the expense of accuracy but this is hunting, not bench shooting.
The post are also dimensioned in a way you can guestimate the distance to the target.
The Leupold can do it by playing with the magnification.
Low light means also 50mm to 56mm objectives.
Now if you have an illuminated reticle you are OK with a heavy duplex, the standard american reticle.
I recently bought a Vari X-VIII 50mm with illuminated reticle (cross) and made it to good use this last Sunday by killing a small wild boar (about 35kg)
As they spotted me, I took a running shot and frankly, without the illuminated reticle I would not have been able to get it. It was about 45 min after sunset and the distance about 30 m.
The only thing I miss on the Leupold is the low magnification that is only 3.5X which is a bit too much for this kind of shot.
I have a friend who hunts with a Swarowski 2.5X10 50mm and the 2.5 setting is better fit for running shot.
I do not see much difference between his Swaro and my Leupold in term of optical quality in low light. The Swaro may be a bit better.
But definitely, the German reticle on the Swro is better suited than the heavy duplex without the red cross.
So to get the best of both world, accuracy during daylight and usability during low light, take the heavy duplex with illuminated reticle.
Compared to my bino, Zeiss 10x40mm, I can see a bit more details in low light than through the Leupold but may be it is just because my right eye although is is as old as my left (I am in my fifties) :grin:
As for the tube diam, only a few high quality brand use real 30mm optics. Some make good use of it for the adjustements, useful for long range shooting were they need a wide range to adjust for bulet drop.