I have a location away from my house, which is a little more exposed to Mother Nature, & where I want to plant a hardy hybrid.
I am considering the following hardy hybrids (all of which I have in containers and ready to go).

1) Thomasville citrangequat (grafted on Thomasville rootstock)
2) Swingle citrumelo (seedling)
3) 10 degree tangerine (rooted cutting)
4) Morton Citrange (grafted on Trifoliate orange rootstock)
5) Sancitchang (grafted on Trifoliate orange)
6) A un-named Trifoliate pomello X (on Trifoliate orange rootstock)_

We occasionally drop down to 10F (-12c) about every 3 or 4 years - otherwise, miid / upper teens can be expected 4 out of 5 years. The freeze events may last a few to several days sometimes a week. We are often wet and the chosen site has good drainage and is in full sun about 20' (6m) away from my house.

Which of the above have the best track record for surviving cold? I know there are many variables when it come to hardiness. This is more of an experiment than anything else. While the tree is young , I plan to cover it with a portable greenhouse (until it outgrows it) So it will be protected from wind chill while juvenile.
Please vote

: It is election day here in Canada - mine-as-well vote for citrus instead of politicians!!

gregn,
I have (in-ground) experiance with #4 only:
Morton citrange (also grafted on PT rootstock) about meter tall planted into ground year ago. The tree have survived local winter (minimal temp -12.5 C, no protection) with no dieback.