I think your letter to NHFC was very well written. It sounds like Mr. Rice is a little confused. He presented the NHFC's policy in one sentence ("We support open carry, period! No exceptions.") and then went on to give what sounded like his own opinion in the following four paragraphs. From his letter I would say he is one of the MANY pro-gunners that is just scared of the idea of open carry. It didn't sound like appeasement as must as just plain ignorance. We fear the things we don't understand and it sounds like Mr. Rice, while he may support the 2nd Amendment, doesn't understand open carry.
I would wait and see what Mr. Krochmal has to say when he replies to your letter. From what I have seen they seem to be a good pro 2A grassroots organization. If there is anything you can do to help furthereducate the people in this organization about OC, I would strongly recommend taking that path. You could see if they will let you write a letter about open carry for their newsletter, or just show up to one of their meeting while OC'ing and then answer any question that people ask you. This could be a great opportunity to educate people that are already leaning in your direction.
That's just my .02. Let us know how it goes.