I just wanted to thank everyone for their well reasoned responses to my question.

Just for the record, I checked both the ambient temperature ( ground level shade) and the temperature of the air entering the condensor of my current rooftop unit.

The ambient temperature was 108F and the temperature at the condersor(half way up) was 125F.

By the way, I encouraged all three HVAC contractors to join this site and read this thread.

Thank you again for your time and consideration.