Little over a month ago I had the 2 systems replaced in my house and at the same time replaced the windows with double pane, low-E.
Had a few issues with the installation and setup but it all has been worked out. Just wanted to post up the first months electrical usage, as this was one of the reasons we decided to change out the old equipment. (Our main reason was for comfort, the old upstairs unit just couldn't keep up well during a hot day here.
Anyway, I am using one portable dehumidifier downstairs (earth berm home), and so far this summer the house stays a constant 74 to 75 degrees with RH between 46% to 48%.
Here's a graph of our weather for June/July 2007 and the same time 2008.
It appears the average temp in 08 has been higher than 2007. Our house is now very comfortable and total electrical use dropped from 2800 kwh during that time in 07 to 2108 kwh in 08. Nothing else has changed as far day to day patterns, no other appliance changes, etc...
There may be a lot of other factors to look at, but so far I am happy to have a cool and relatively dry house along with a 25% reduction in electrical use.