At the moment (345pm Melb) the outside temp in my fernery (in the shade) is 37 deg. Hardly a cloud in sight, it is estimated to reach 40 deg later today.
Inside my house courtesy of my Evaporative Cooler it is presently 25.6 deg. This will probably peak (based on past experience) at about 26-27 deg later. It is very comfortable in my house with nice cool breezes flowing out of targeted windows.
My 12y/old Evap Cooler whilst not as efficient as the current day models, is obviously doing a very good job whilst consuming approx .5 kW per hour to run. Particually so, given that my retro fitted ceiling insulation is less than optimal, and there isn't any sarking under my tiles.
Regardless of all of the aforesaid scientific information tendered here, it should be obvious that the lower my roof space temperature is, the more efficient my evaporative cooler will perform. After all, you get what you get with evaporative cooling. There are no temperature settings to be had, no comfort levels to be set.
I live close to the City in a very established area. Almost every nearby property would have similar insulation limitations as my house. It is my very firm belief that they all would benefit from lowering the temperature in the roof space, which is exactly what my Solar Whiz does.
May be, the conversation could differentiate between the benefits of forced ventilation in regard to new-builds with optimal insulation, vs the great number of houses without. In a perfect world we would all have our houses perfectly oriented and insulated better and we would all have white roofs.
Also, the argument could recognise that every house doesn't have "power thirsty" Refrigerated Air-conditioning.
For the time being, I certainly will not be disposing of my Solar Whiz...it does a very good job, albeit in conjunction with other limited heat abatement measures that are possible in an older or established home.