Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
-region: This option sets a write mask for the region you define. In IMv6, a separate image was cloned instead, operated on, and the results were composited to the source image. In addition, the draw transformations are relative to the upper left corner of the image, previously in IMv6 they were relative to the region.
Sure, you can clone the image, operate on it and composite the results back to the source image. This is exactly what IMv6 does, -region was simply a convenience to do all the operations with one -region option.