re: How far should home A/C be from the setpoint?

In the five or so homes I have lived in, getting below 70 in the summer has always been a challenge. My current new system will drop the temp from 78 to 71 in less than 30 minutes but from 71 to 68 would take hours during the day.

I also have a sensi and it works great. I think your old thermostat may have been a couple of degrees off compared to the sensi and you are just trying to get the temp down too low.