I lived in NYC for 6 years and had a wonderful time, pre kids.
I think most of the considerations here should be disregarded. You aren't going to be shot or denied healthcare. Actually, you'll almost definitely have much better healthcare than you get on the NHS because your DH's job will cover insurance. The political bickering is annoying but you can tune out, and we have plenty of that in the UK too although granted it's not quite as divisive.
Actual downsides that will affect you are things like vacation allowance, working hours, being an outsider and having to make new friends. Inconsequential cultural differences might make you feel lonely: they like different sports, the sense of humour is different, political correctness is pretty extreme there so you have to be careful what you say.
other things to consider: what if one of you wants to leave but the other wants to stay - who "wins" that argument?
You haven't mentioned kids which is another huge consideration. Maternity rights are crap. I know one woman who gave birth to a very ill premature baby and was asked to go back to work immediately because "the baby is in NICU so you don't need childcare" (she told them to fuck off, thankfully). Another woman I know was back at work 2 weeks after a c section.
on the plus side, you'll have great holidays around south and north America that you probably wouldn't do otherwise.