Swingle is an excellent rootstock where it is well adapted. It does well on loamy soils, sandy loams and sandy soil. It does poor when grown on heavy soils or soils high in salinity. As far as freeze tolerance, trees grafted on Swingle generally have good freeze tolerance, but they are typically somewhat more susceptible than those on Trifoliate. Scions grafted on Swingle typically have good to excellent yields, even somewhat better than trees on Carrizo. I don't know much about US 897, perhaps another forum member can help you out on that rootstock.