I’m curious about your assertion that having a V60 made from a thermally conductive material will be better than one which is an insulator. Why do you think this will result in a more even temperature?
If you have a conductive material, more heat will be lost from the water (as it is transferred from the water to the V60 and then to the air). In theory, the V60 and the water which is nearest to it will be slightly cooler than the water in the middle (this is known as a temperature gradient). How much cooler depends on residence time and the ambient conditions (i.e. is it windy/hot/cold etc).
If you have an insulating material, less heat will be transferred through the wall of the V60 (which should mean it’s outer surface is cooler). The inside edge is heated by the water, but because not much heat transfers through it, the wall will approach the temperature of the water (at which point, heat transfer from the water to the V60 will reduce). There will also be a smaller temperature gradient between the water nearest to the edge and the water in the middle (which you could describe as having a “more even” temperature).
Sure, having a conductive material might allow some heat to be transferred from the top to the bottom of the V60, but I don’t see this being very significant.