Fair point, although the tip of that thermometer is only a few mm away from the balls, I can't really imagine convection would make up a full 160+ degree difference. Luckily it's easy enough to test by gently (or not so gently) blowing through the air intake on the bottom.
(15 mins later)
Yeah, I was able to get it up to 351F by experimenting with the convection airflow, but that's still well shy of the advertised specs for the highest setting.
Edit: It appears that at least one unit had
issues with the temperature sensor, maybe that's what's up.
/shrug