I would keep them potted up for awhile. Those are pretty small; the rule of thumb is generally the larger the plant the better its chances. From what I've seen, bigger plants grow much faster than small, and the small plants grow even slower if in the ground in suboptimal conditions. In the deep south that size would be acceptable to plant, but I would think not in a cooler climate. I'd keep the smaller plants in containers until they get character leaves, I'd keep the trachy in a container for at least a year or two.

I would hold off on the brazoria since its in shock . The Louisiana should be fine in your zone. I had several seedlings come through winter with only a pot covering them. Which included a Louisiana, brazoria and 2 Birminghams. I have 2 T. princeps and have seen alot of negative feedback about their hardness. So I would be sure to protect during winter.

The plants look awesome and now is definitely the perfect time to plant palms, but I do think that those palms are still a little too small to go in the ground. Maybe next year or the year after. Once it has a nice set of adult fronds, it should be ready!
-Alex