The answer is yes, especially if the rose is grafted onto fortuniana.

Bushes grafted onto F will be much larger, and produce more and bigger

blooms.

Hi Bart! Agreed, but also whether the stock is more suited to the conditions than the original variety. For years, there was a large bed of Iceberg at The Huntington Library. All but one plant were budded to Dr. Huey. One died, and it was replaced by an own root plant rooted by the volunteers. That was the most vigorous of the bunch. Now, it COULD be that a more climbing type was selected for the cuttings, resulting in a more vigorous replacement plant; or it COULD be that Iceberg own root was more suited to the combination of conditions there than Dr. Huey, or both. We'll never know for sure, but you see the potential questions. If the plant is weak, budding it to anything more vigorous and/or better suited to the conditions can greatly change the habit. Something extremely vigorous could actually be inhibited by budding (like a dwarfing fruit tree root stock) if there is incompatibility between the scion and stock. There are MANY potential issues to consider in answering the question, but in general, more than likely.

If any of mine are grafted it osis on Dr. Huey. I see that the grafted may seem larger at first but after a few years I do not see much difference in zone 6a.

I'm almost positive the variety of the rose has so much to do with how it grows. Own root or grafted. I have Pink Enchantment and Sunny Sundays own root at a local public garden that are every bit as big if not bigger then the grafted bush's in the garden. Then there is an own root Dark Desire in the garden that is going on 4 yrs old and is no more then 2 ft tall and wide with floppy canes. Some varieties are natural monsters and others need all the help they can get.