Mine were planted years ago and have sunk into the ground and are now own root. They do very well. For a time , the only HT that Antique Rose Emporium sold was Chrysler Imperial on ownroot. They do very well here. Truly a great rose in my opinion.To be honest, none of the roses grafted on Doc Huey have done better than ownroot here. Multiflora may be different and any rose grafted or budded to Fortuniana really stands out growth wise.Just my observations.

Funny you should ask. :P CI is one of hte only HTs I've kept. Love him.

Couple years ago I was dead heading the lazy way (snapping) and broke off a cane of CI. Feeling rather guilty and stupid I stuck it in the ground next to him. It survived. It is currently doing nearly as well as its grafted parent. It blooms about as much. Stays a bit shorter but that's only because my winter kills them both to the ground each year.

Its probably worht a try on its own roots in a warm zone.

I bought a virus indexed own root CI last fall and although it's still very small (10" pot) it's already sent up 2 true basils (ie: from the soil, not from a cane). A friend of mine grew CI own root and swears it did fine and even better when she finally planted it in the ground. I wasn't so sure since CI isn't the most vigorous rose even with the grafted rootstock to give it extra oomph. The only thing I would be cautious of is finding an own root CI that's not RMV infected. A cutting from an infected rose, even if it's touted as own root, would still have issues.