Unless it's some oddball experimental design, this is a very, very strange idea. You aren't going to tell much about the airplane in silver or clear that will usefully translate to the same airplane 4-10 oz. heavier. And not only is it abnormally light, it's also abnormally flexible. Paint adds significant rigidity, and that will very signficantly change the characteristics.
Also presumably, you aren't going to fly it for long with clear or silver and then be able to finish it. You'll get a lot of oil and that will screw up the paint. So, you can only fly it for a little while, and that means the chances of finding something subtle is negligible. If it's a gross problem you should be able to find it by inspection - shouldn't have to fly it to find it. I have seen airplanes that took the better part of a decade to diagnose.
And, the entire concept is based on the idea that you don't want to find something and have to cut into the paint job later to fix it. I hardly see an advantage to cutting into 3/4 of a paint job (i.e tissue, clear, silver) over a full paint job.
I'd be very curious to know if 1, someone actually did this and 2, found something, how much time or effort they think it saved. And how *often* this works out positively.
Brett