It might still be desirable to fix this, but it may be quite some work (for limited benefit) so I'm not sure if it will happen. The problem is that the CubicVertex encodes vertex positions with one byte per component, giving a range of 0-255 for x, y, and z. We don't want to change this class as it is very compact and sufficient for most purposes. The fix would therefore involve templatising the CubicVertex class on position type, or introducing a new vertex type and further templatising the extractCubicSurface() function on vertex type.
Users are generally expected to break their world down into 'chunks' which would be smaller than 256 voxels, and the issue is not applicable when PolyVox is used in this way.