Hi Bussone,
I have both Morton Citrange and Thomasville Citrangequat, both on Flying Dragon rootstock. Both are about eight feet tall. They are two completely different animals. (Animals? Well, they both do have a bit of a bite to them.)
The Morton Citrange is a 50-50 hybrid of an orange and a Poncirus Trifoliate and has large orange sized fruit that typically ripens in late November, here in my short growing season location. It tastes like an orange, with an off-flavor I don't enjoy at all. But that's subjective; a local board member loves them and comes to get them in December. It bears relatively heavily; I get fifteen pounds or more, most years.
The Thomasville Citrangequat is a cross between a Citrange and a kumquat. It has kumquat sized fruit that can be harvested green in November, here. The flavor is like a Key Lime–a lime flavor with a touch of bitter–which I enjoy and use in a number of culinary applications. It's rather shy bearing; I typically get less than five pounds.
The Morton Citrange is much hardier than the Thomasville Citrangequat. A two week arctic blast in January 2017, with one low near 8F, caused extensive small twig damage to the Thomasville; the Morton Citrange snickered at the cold and had no discernable damage. Based on this, I'd guess that the Morton could survive down to Zero Fahrenheit, or maybe a bit lower, making it a zone 7 plant, whereas as the Thomasville is more of a zone 8 plant. Although, being in Pennsylvania, your arctic weather events would last much longer than mine, based on my experience in living in Michigan for thirteen years, so that may have a bearing on survivability of the Morton in your location. The Thomasville wouldn't survive at all in your location, without protection.
Hope this helps,
Jim