Stained Glass In A Window That Opens

Sometimes a client wants stained glass in a window that opens, either for privacy or to add color or for a combination of reasons. Because I think that stained glass should be mounted on the interior side of clear glass whenever possible, mounting stained glass in an opening window is certainly possible, as you can see in this photo. While stained glass is fine for outdoor applications, too (I once did a commission that was 22 feet wide and 15 inches tall that was mounted to the top of an outside wall to give a hot tub more privacy), I believe that installed stained glass (that is, not hanging) should be mounted on the interior side of clear glass for two reasons. First, this increases the heat-loss factor, which is helpful in both cold and warm climates. And secondly, even if I can deliver a totally weatherproof stained glass artwork, who's to say it will still be weatherproof ten years later? So why would it make sense to expect an expensive artwork to keep out the weather forever when a relatively cheap sheet of clear glass will do that just fine forever (assuming it was caulked in well at the start)?