I own two EX330s as I'm using them for the basis of developing a 200 level circuits class.
As your question is in regards to the thermocouple, my experience with it is that it isn't just "on edge" of accuracy, but that it's downright erroneous. The meter presents a questionable answer below 45F (it seems to plateau at around 35F), and as it goes hotter, it might be +/- 3-5 degrees F. What is funny is that I move the exact same probe to my Fluke 179, and I get different, repeatable, and accurate results.
The EX330 is fine for a probes on a voltage reality check, but it isn't something I'd recommend using for any amount of precision.