Fortunately I just got a grafted A.S. Its a good sturdy looking bare root plant. I honestly believe that grafting is a very useful horticultural tool that shouldn't be minimized. In some cases it may make the difference in its final performance. Locally nurseries use R.multiflora ( not Dr.Huey). I would love to find a better rootstock for cool summer climate like mine. Our summers barely reach 90ºF for a few hours on a few isolated summer days. The overall temps are much lower so rosebushes grow accordingly less. So does the soil temperature rise slowly and doesn't accumulate anything near to that of the temperate N.Hemisphere. So a rootstock from wild species ( or not) better adapted to cool soil growth ought to provide a good root base onto which I would graft cultivars that are own root or grafted onto warmer region multiflora. I also think that a better rootstock will provide a healthier plant because if the match is adequate the plant will be stronger and have better defense mechanisms to fend off disease.
Arturo