Unfortunately the industry changes very quickly, I dare say as fast as IT. Mini-split (ductless) unit change in some way about every 6 months. Window units change almost as much. The industry treats window units like Bic lighters (they aren't really made to last). The absolute best way to find out the quality and noise output is to check the reviews. As far as efficiency goes, look at the description where it says SEER (Seasonal Energy Efficiency Ratio), the higher the number, the more efficient. Like MPG (Miles Per Gallon) on a car. I hope this answers your question.