I have a 80ch and have found some 40ch radios come through distorted to me but sound ok on other 40ch units.
The reason would be they are probably transmitting with the full 5 KHz deviation and the 80ch units have their receivers set up to handle 2.5 KHz deviation.
I think all 40 channel units should be banned and everybody should have to buy a new 80 channel unit from my work.