I'd be cool with America making it. They've proved time and again that they can do great shows. The majority of U.S. T.V. may well be awful, but their good stuff (particularly on cable) is at least as good as our top shows.
We'd just have to ensure that a suitable showrunner and production crew were involved, with a Brit employed to vet dialogue and Britishness...
If BBC America were to take over funding the series, I wonder if they would keep its production in the UK (essentially renting the soundstages from BBC Wales) or if they would relocate the production to Toronto (where
Copper was and
Orphan Black is filmed).
As for who would be behind the camera in such a scenario... well, that's an interesting question and one I hadn't ever considered. If the actual filming were done in the UK, I suspect they would opt for local talent. If production were relocated to North America, the writers and producers might be more multinational.