I'm not an expert but have read that the human eye pupil only allows so much light in and anything over that amount does nothing to enhance your low light view. Bottom line is that a 1" scope to that allows the maximum amount of available light thru is just as bright as a 30mm that does the same. Don't know but read from others who do.
It is also said that a high end 1" scope is far and away better than a lower end 30mm, not only for light transmission but overall.
In my hunting and shooting I have not found the need to change from 1" from which I have many, to 30mm from which I have none.