I'm pleased with the install. The guys were very professional. They took time to reroute the drain plumbing for better drainage and added a cleaning port. They reinforced the closet floor where it was sagging. They stayed past dinner to finish the job the same day.
The unit - blows a lot more air, so it's louder. I added a second air return in the next room to relieve some restriction and noise. The air it blows is colder. That means it cools MUCH more effectively than the old one. I could tell within 5 minutes. The outside unit is much quieter, which is nice.
The weather has been mild so I really can't tell about power usage yet. I expect major savings - about 3/4 of our electric cost is heating/cooling. If this knocks a third off that, it'll be 1/4 off the total bill.
Adding ventilation is next. I bought some sample ridge vents to study and inspect.