I just had a mitsubishi 18K installed and love it. After doing all kinds of research I definitely found out that brand X 18k unit is not the same as brand Y. My bonus room is less sq ft than that, but very hot with black shingles. After running it, I am glad I went with the mitsubishi and the inverter system. It will slow down the compressor when the room reaches within 4 degrees of desired temp and also has a dehumififier (drying) setting. Then when the unit starts, it does a slow start (not sure of the proper term) instead of slamming the compressor on full tilt. Hell, I even had trouble hearing the outdoor unit run once the room was close to the set temp.