I can't really tell you if I have saved enough to cover the expense of the unit, but it has come in handy for monitoring my electric usage and also it estimates upcoming bills. IMO It was just another toy.
In my home the A/C (2 ton 14 SEER) is nowhere near the biggest energy user. (But I am in a fairly cool climate that just saw our first 90+ day today.) The dryer, stove and slew of electronics not only add to the heat load but consume most of the electricity I use, far more than the A/C.
Also...the OP posted that you cannot buy an Energy Star dryer, which I believe is correct...but the energy star front load washers use alot less water and also spin dry alot more effectively that older traditional models. If you do not have one you would be surprised how dry the clothes are when they come out of the washer.