I went many months before I opened my B2 for its first cleaning and the insides were spotless. I'm guessing you put a massive glob in and then immediately cleaned it after it cooled? If you leave it turned on for a bit it'll burn everything off.
You said you noticed a difference (drop)in flavor going from 3mm to 4mm? If anything flavor should have improved as there is less surface area for the dab to touch the ruby. 3mm is more restrictive but more efficient for heat retention because of the increase in surface area.
Between my B2 with 4mm and B1 with 3mm, the B1 has a WAY more open airflow. I haven't tried any of the new heads as I'm very content with my airflow.
As a side note, if you dab a lot and want the pinnacle of flavor from CH, look at the T-bucket with a Sapphire insert dish.
That was the expectation for switching to 4mm and lowering the temp
Did not experiment with temps which was a mistake
My experience was a muddled flavor at the temp I was using
To many variables including the flower to pinpoint any one reason for lack of flavor
Dropped quite a bit of concentrate into the nut so the rubies got tacky
One thing I should explain is that I vape 1-3 times a day to charge my cannacaps
Dont leave my ball vape on all day so the rubies were dirty when I changed them
Honestly forget to turn the heat up for a few minutes to burn off any residue
Habit that needs development
Newbie, in case it was not apparent
Using an e-nail for concentrate