I think the mystery is when you have "real world" construction techniques that don't allow for super sharp shapes then what is the best shape to have. Rounded or squared off. For this dulled down trailing edge the optimum is the squared off shape. Rounded shapes tend to promote flutter by the air cyclicly holding onto first one side and then the other. Like a flag in the wind. A squared shape forms a little turbulent bubble in the wake of the blunt edge and the air flows around that small turbulent "wire" in a far more predictable and consistent manner.

Seanreit, for jets where speed is the goal you should be aiming at reducing your trailing edges down far more than that. I'd suggest something I used on some sailplane parts that never ended up seeing the air but the method worked out well. Use your 1/64 ply on only one side with balsa on the other. Ideally you would make up some trailing edge edging stock that has the ply on one side and chord wise balsa on the other. This edge cap would then glue to a thicker and normal spanwise trailing edge to form a small extension that can then be sanded down really fine right to the point where you're feathering out the 1/64 ply by a little bit. The chordwise balsa on top that builds up this edging will help provide a lot of stiffness. When you finish glass over all the works the glass and resin will bond it together and add further stiffness. If you can do try to let the glass cloth run out past the edge of the ply by a 1/16 inch. Then feather THAT out for a super sharp edge that should be decently strong. Just dub it off a hair so you can't cut yourself on it.

If you do that your surfaces will have the least drag possible and far less drag than 1/8 flat edges.