For what it's worth, Bacupari miudo (Garcinia brasiliensis?), Mexican Garcinia, Achachairu all survived outdoors on the rooftop this winter here in Northern California, and Lemon Drop Mangosteen has survived two winters up there. They weren't too happy with wind (Mexican Garcinias lost leaves now and then), but they're doing fine and growing again. Granted we've had two mild winters in a row but the city had two nights of 33 F this winter and last winter had two nights of 30 F -- officially zone 10a. The rooftop is warmer (altitude plus thermal mass of the building) so add a few degrees.
I was (pleasantly) surprised they survived. Just hope they grow faster than the current rate of two leaves every 6 months.