Yes it is sufficient, but that's not the question is it? There are a few shops selling Bromptons in NYC. So I think you should test ride (and fold and carry up stairs) until you know which you want.

David Lam at bfold should accommodate you and you might want to try the Carry-me while you're there since it can have a wider gear range than the 3 speed Brompton, be lighter than the two speed Brompton, and be cheaper than both. It also folds smaller. Disadvantage is it doesn't fit larger people (which isn't a problem for you) and it has smaller wheels which some people don't like.