Disease resistance depends primarily on the variety. Generally speaking, a rose on its own roots will be no more or no less resistant than the same variety that's grafted onto another rootstock.

In my garden I grow both modern and antique roses. I prefer old garden varieties on their own roots, but I have a distinct preference for modern roses that are grafted. I don't understand why there should be a difference between the two, but in my experience there definitely is. I do occasionally purchase ownroot moderns, but ONLY if I can't get the variety as a grafted plant.

As for your question about DA roses, I have to defer to others here who have experience with that vendor and his roses.

I believe that all roses from DA are grafted. They do very well. However, the roses from Roses Unlimted are gallon size and they will do well from the start in your yard. There are advantages to both. But I think long term, own root is better.

Roses Unlimited roses are usually quite big when they are shipped. As far a own-root and growth, once you get them out of the smaller pot and either into the ground or larger pot they really take off and you will not see difference.

I prefer own-root rather than grafted and I have anything from minis to OGR,and modern roses (including Austin rose) that I purchased as own-root. Only 3 of my 60+ roses are grafted.

I've got both own root and grafted. I prefer the grafted plants from Palatine Roses because they start out so large and do so well the first year. But the own root plants will do almost as well especially if they are bought early in the spring. There are some plants where you would want to be assured of a virus free version, and that almost always means buying own root. Own roots are also easier to plant because you don't have to plant them as deep, and you don't have to worry about suckers from the rootstock.

Grafted have not worked well for me, so this year I invested in several own root roses. Most of them are OGRs with a few hybrid musks and polyanthas.

At least I won't be getting any more of the wild red roses (Dr. Huey?) in the spring. If own root has some die back, there's no competition with a graft root stock, which always seems to take over...but I'm in zone 4 :)

Austin definitely supplies grafted roses, they arrived in excellent condition and were HUGE! I had to break out my BIG tub to soak them and still only got three in at once. The roses were vigorous growers last year and this.

But it's too late this year for bareroots. Definitely not too late for bands. I LOVE the immediate gratification of grafteds, but sure hate to dig those big holes. ;o)

If it were me I would send for a few bands to satisfy my rose lust, and plan to order the rest grafted or own-root next year.

All my roses are own root. I agree with greenhaven regarding not getting grafted now. Make your list and order for spring delivery.
I got several from Roses Unlimited this spring. They're all growing well. It's still early enough to order their large plants.