I don't think that's a fair assessment. It was drawing on the same worldbuilding, but it was another story about the Klingon court/penal system, so naturally there were some recurring ideas. The actual story it told was quite distinct. Maybe it did go a bit overboard on the TUC homage, but "ripped off" is an overstatement. Now, that's really pushing it. The only thing they have in common is that they're both set on Risa, which had become an established, recurring setting in Trek by the time ENT came along. Now, that's the one example you've offered that's actually valid.
I like Terra Nova. I think it's kind of interesting how the vocabulary was changing, just because the children growing up wouldn't have known the specific word they wanted. Reminded me of my kids when they were just-verbal; they'd make up conceptual words when they couldn't find the right noun.
I don't see how the true extent of radiation-polluted territory would have affected the decisions of the Terra Novans. For all they knew, the entire planet was polluted; certainly this would be the case if they were under attack by outside intellects (evil Earthlings), as those would not leave a way out for their victims. So, no attempt at walking out, ever. As for checking out on Terra Nova, the problems would not be solely logistical. Quite possibly, Vulcans would count trips to Terra Nova as "deep space" sorties, and would deny permission from humans - going that far out would incur the wrath of Bug-Eyed Monsters and other things humans were not ready to confront yet. We know humans found colonization targets much closer to home eventually - first at Mars, then supposedly at places like Alpha Centauri - and those would both reduce human interest in the fate of Terra Nova and allow Vulcans to claim that no real curtailing of human spaceflight was being done. Also remember that this was all covered in dialogue. The colonists themselves said they wanted no checking out; the Vulcans would have done it for Earth, but Earthlings knew better than to ask for something that carried an unknown price tag; and with these things given, the nine-year trip there and back simply wasn't worth the effort. Timo Saloniemi
The original post-apocalypse Novan generation were young children, in this way the episode reminded me of Miri in that children grow up without the influence of adults and their perceptions of the world are different because of that.