It’s not even trying hard. The unit in my bedroom gets more use than the rest because I drop the temperature from 79 to 77 while I sleep, but even with the recent 90+ degree days, the compressor seldom needs to run. That leaves the humidity on the high side, but one or two degrees cooler makes the comfort level pretty much the same.
Another sign that it is not trying very hard is the fact that I have yet to need to empty the drain buckets. The one in the office and the one in the spare bedroom barely have any droplets in the line, and nothing that has made it to the bucket itself. The one in the main part of the house has about two inches in the bucket, and the one for my bedroom is maybe a third full.
I know it won’t be so easy when winter rolls back around, though. Maintaining 75 when it is 95 outside is much easier than maintaining 70 when it is 20 outside. That will be the real test.
Grumpy Bastard 
My grandma had a heat pump for a long time. She supplemented with central air in the summer, and a wood stove in the winter (the heat pump kept it at around 59-65 degrees). It did keep costs down, though.
Aren’t all heat pumps essentially air conditioners that are reversible, enabling the air handler to pull from either the hot or cold side?
They do suck as a heat source below a certain ambient temperature, though, which is why most are either paired with a real furnace, or equipped with an “emergency heat” feature, which is usually a heat grid inside the air handler. Not sure how that works on split systems like mine, if they even make such things. My particular model lacks anything of the sort, meaning that teen or lower temps will require breaking out the space heaters or other heat source.
I’ll monitor the electric bill and update later on the cost for cooling, and effectiveness/cost when it comes time to switch to heat.