How hot?
Too hot to touch is still way below the limit for most ESCs. I noticed on one of mine that the thermal protection cuts in at 95 degrees C. That's hot enough to take skin off.
The 75-80 I see when running normally is also too hot to touch.
Get a non-contact (IR) temp gauge and find out how hot it really is. I bet someone at your club walks around with one in their pocket (at our club, that's me
)