Looks great. I think you will like the foam.
6/29/06 - 7/29/06 880 sq feet in building used ~3700kwh
6/29/07 - 7/29/07 2183 sq feet in new house ~2180kwh
To be fair, the water well is still on the building meter, and I had/have electric water in the building but a tankless propane water heater in the new house. And, this July was not quite as hot as last year I don't believe. But still, we are very pleased.
We keep it very cool and comfortable and have had no trouble keeping it as cool as we want.
I didn't do the full envelope, but I think you should get similar results plus the benefit of a cool attic.
By the way, with my radiant barrier and ridge vents I put the thermometer in my attic last weekend when the temps were 101 to 104. In the middle of the day the temp in the attic was only 105, which I am also very pleased with.
If you foam the underside of the decking you won't need the techshield radiant barrier, it won't do any good. I guess you are already way past that stage however.
When they foam the house be sure you go ever it closely. Especially the attic areas to make sure it cannot leak. Since you are not insulating or ventilating the attic it is critical that you don't have any air leaks into the attic from outside. Make sure you are satisfied with the job and get them back if necessary. If you use the same contractor I did, they will do a good job, but it is your house and you will have to be firm.