Since sharpening affects the contrast at the edges, it is possible that something would be pushed out of gamut. If you have resized your image for printing and do the output sharpening, why not wait until the sharpening is applied before soft proofing?
I use Qimage to resize my files on the fly, and I use Qimage's very smart output sharpening, so I softproof my files before uprezzing and sharpening.