I can't help you too much on the contour option but I can let you know my experience with the regular scales.
They measure 17.5mm near enough 11/16th of an inch.
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I mainly use my ESSE knives for hunting related jobs. Skinning, cutting meat, dispatching animals etc. I find the flat scales offer a good grip when covered in blood. I've never thought to myself, I wish these scales were rounded. But I must stress I don't have experience working with wood or "bush crafting" so it may be a totally different story for those guys. I did have an ESSE 3 with contoured scales and I'd didn't like it. It just didn't feel right to me after years of the flat scales.
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I hope this helps you out a bit.
Dan
