My newly bought Valencia also seems to be as tough as nails. I bought it as a strong looking bare-root (in a bag, with sawdust around the roots) about 4 months ago and was planning to put it in the ground, but didn't have a spot ready for it yet. So when I thought I was ready to plant it (maybe a week after buying it), I soaked the roots in a bucket one night, expecting to plant it the next day, but didn't get around to it.
So as the days went by I ummed and ahhed about whether to put it in the ground or in a pot, to start with, while the plant was still in the bucket of water. It was also left outside and while it was in a very shady spot, it still got a bit of direct sunlight each day and as the weeks (yes weeks!) went by, some of the water evaporated, drying out the roots on one side of the plant (as it was leaning to one side and some roots ended up out of the water, after the evaporation). I could see that while the plant was sending out new season's growth, it was struggling and not looking healthy, so after about a month I decided I had to either plant it, put it in a pot, or throw it out, so I decided to put it in a pot and see if it would survive.
Well survive it has, and while it unfortunately lost the strong cane that was directly above the roots that dried out, the rest of it has grown well and there are now about 7 strong buds on it, with the first one just about ready to open out any minute. Even after all that, there has been no real sign of any BS or mildew on the plant, even though plenty of other plants in my garden have had one, or both. Very impressive.
I also saw some of these in flower at a local rose nursery, the other day (one of which is in the pic, below) and was really impressed with the big, beautiful buds and blooms. It was the first time I'd seen any of these in person, that I'm aware of, so I was glad I took the chance on buying this one (as I don't usually buy a rose that I haven't seen for myself).