Isn't the Grosvenor across the street from Downtown Disney? While crossing that street may require a bit of hustle, even with the walk lights, it seems to me it'd be faster just to walk. If I'm remembering correctly, the HPB buses run on a loop every half hour AND drop you off somewhere in the middle of the parking lot. It just seems to me that walking over to the DTD bus stop would be faster, unless the HPB bus was right there (and because it's a loop, the Grosvenor is the last pickup).