Depends a lot on the plywood. I wasted money on some Chinese crap that had a layr of bamboo strands inside. It splintered so badly it was completely useless. Baltic Birch, however, can really look nice with a roundover. Almost never use anything but BB anymore, only if I need a piece longer than 5 feet. Then I look for ply with many thin layers and pay a premium.
Another approach is to put edge banding on the ply and roundover the solid wood. This will be more decorative than a ply edge. A few years ago in an Amish area, I saw shelving of BB ply with a bullnose edge--really interesting and colorful.
1/8th would ease the edge, 1/4 would be a little more likely to tear out or spinter because it will attack 3 to 4 layers, each with grain in opposing directions.
The more I do, the less I accomplish.