If you have a couple more hygrometers laying around I would add them at different levels. My cabinet varies quite a bit from top to middle to bottom where I have the humidifier. Your cabinet is much nicer than mine, I have an old model. What's with the big round hole at the top? Does it have some way to pump air from the bottom up the sides or back and out the top?
Also looks like the door on yours has extra Spanish cedar that I guessing when closed the Spanish cedar makes a nice seal all the way around. Mine doesn't have that and I think that's why mine varies so greatly. I need to upgrade, but it's hard to justify when I already have one that works, just could be a little better.
Looks great!