Getting a good alpha channel around objects is pretty hard live and with high megapixel counts. If you want to do this in-camera or within half a second, it's going to be sloppy for now. Essentially you have to check out a bunch of different 'magic wand' settings and compare the results, and there's no validation of those results until the user sees them. But yeah, it should definitely be possible to scoot the blur point "backwards" a bit.