They generally work fine until you hit 95 degrees, then they really don't help much for anything more than a fan.

The extra moisture in the air tends to swell doors and frames in the summer, making them hard to open in some cases.

Pads should be serviced/replaced yearly, water turned on in spring and off in fall and drained. It's not hard to maintain them, you just need to know what to do.

I have no experience with heat pumps, can't help you there.