Malus coronaria as a rootstock?

I had a few seedlings of this variety planted out but were being choked off by native competition. I dug them up early spring and for an experiment grafted on some known varieties. 2 of which are King David & Myers Royal Limbertwig, in my small nursery they kept up vigor with the likes of B118 & Ranetka graftings.

Has anyone used this as a rootstock? If so, what was your experience with it? Did you notice anything about it you didn't like? How hardy did you find it to be?