Planting Flying Dragon is definitely a good idea, it is very ornamental tree, but sometimes it is tricky in zone 6.
I know many trifoliates doing great in this zone for many years, but I also know about many failed attempts. Microclimate and age of seedling can play a role.
It is important, how long and tough the winter in area really is.
I know that doyen of citrus growing in Czechoslovakia Mr. Urban talked about selections he made of poncirus from former Soviet Union to be able withstand winter in his area and other areas, especially with higher sea level, it means longer winters.