Our own root roses were purchased from Heirloom Roses and per there instructions I planted 1" deeper than it was in the pot.

JIM

I was at at district rose society meeting where a presentation on the Easy Elegance roses (EE are own-root) was given & the presenter recommended planting 1" deeper also.

I plant mine 1 inch deeper except for those that have only one main cane coming from the potting soil and branching out a little higher up.
I that case I plant up to where the branching takes place. I actually plant so an inch of the branching is covered. This may mean the bush could be planted 1-6 inches deeper than in the pot, depending on how high up the branching takes place.
It gives the plant more support and a fuller bush with more canes growing from the soil. Those portions of cane covered will root.

I plant mine a little deeper than level, but I really don't worry too much about it. The nice thing about own-root is that as long as the roots are alive, you'll get your rose.