It could probably pay for itself in short order. Take a close look at the current draws, and compare. The scale is linear, so you're getting a nearly 50% increase in efficiency. Now, I'm not fully familiar with how they rate it when it is a heat pump...it may be the same thing as the a/c only version...just factoring in the increased efficiency when in heating mode. If that's true, it isn't worth the difference if you don't need heat. Do they list cooling only efficiency?