My pure Ichang Papeda grafted on PT could barely withstand the winter in zone 8a. It barely survives, but most leaves would be damaged and fell off.
It is true that the leaves do not survive very well, and judging by the behavior of the leaves we could be inclined to think that it does not seem to have so much cold tolerance, but I wonder if this is necessarily indicative of how much cold it can tolerate. What I mean is that maybe Ichang Papeda might behave a little bit deciduously (a little like Poncirus trifoliata perhaps). Does the plant seem to suffer branch damage? That might be a more accurate indicator.
Ichang Papeda also flowers and fruits during winter which make it a useless source for hybridizing program unless you just want an ornamental piece of citrus.
I'm not sure this is true. I saw a large Ichang papeda tree on the top of a small mountain in Portland, OR, with fruits that appeared reasonably ripe, at the start of November.
The quality of flavor and edibility is not really too far less than Yuzu. (at least in my opinion)
The inside reminds me a little bit of a Kaffir lime that maybe is not fully ripe (although I realize Kaffir limes are often only considered marginally edible).
But I think this is probably very much dependent on personal opinion. Those who like kumquats and lemons would probably be more likely to find Ichang papeda to be edible.