This subspecies has been slow to develop for us, taking a year plus to reach maturity. We more-or-less gave up on them as a stand alone variety, but have utilized the best of the 80 or so seedlings we grew as parents to cross with other guaranitica strains. Some success in the first generation, much more so in the second. A couple were sent last year for evaluation to nurseries in MI, GA, FL, PA and CA. Reports last year were positive, but it is too early in the year to be definitive about winter hardiness.
Bottom line is, this is a great species for hybridization but from our experience not much on its own.