I have a lovely Peace from a friend's plant. Does this get big eventually own-root if given lots of TLC?
I don't know how strong or vigorous Peace is own root but how old is your rooted cutting? Own root roses do take several years longer to mature than grafted ones. I'm pretty sure that Peace was one that was never even tried own root and went right to grafted from the get go judging from its intro date. I'm not sure if anyone knows how it does own root.
Another thing to consider is how old your friends Peace rose is. I've heard that the newer ones aren't any where near is good as the older ones because they've been cloned so many times.
My rooted cutting - well I can't really count it's chronological age because I first planted it in a horrible place where it kept getting eaten by rabbits. I put it in its current site 2 years ago maybe. My friend's plant is magnificent. Prettiest one I've ever seen, with softball sized flowers. I don't know how old it is, but it is obviously a happy 5-6' tall plant.