I never thought the point of a biscuit test was to make perfect biscuits, but rather to have a visual of how even things cook... Either way, the test showed me two things... ( or at least it and your commentary did... ) First thing it showed me is the heat distribution isn't too bad... The second thing I learned from it, is there is no 450F setting on the Camp Chef...
I think doing the biscuit test at the closest setting you could get , and making note of it, is perfectly fine.
Now, as for not having a 450F setting in general... that's shame. I really don't hardly understand this day and age , why a wider range of temperature settings can't be put on a digital pellet grill control. Surely to add ability to set in virtually any increment is not that difficult to do.