I agree with both statements completely. In zone 4b-3a I think a guy would be much, much farther ahead focusing on apples/crabapples instead of chestnuts. Even winter hardy pears would be a better choice in the colder zones.
Number 2 is exactly what happens to the vast majority of chestnuts planted here. I do have a couple different varieties hanging on..but they aren't growing worth spit and apples/crabs planted at the same time will be producing mast in another year or two. I sincerely doubt any of my chestnuts will ever live enough to make a single bur.
There is a forum member (not sure he ever comes to this forum anymore) who has some Dunstans growing an hour+ north of the Twin Cities. He has lost some to winter kill, but still has some hanging on.
Bottom line - if you want to mess around and try to grow something well outside of their range - go ahead. Just don't expect them to ever produce any quantity of mast and don't be surprised when (I'd say when, not if) a bad winter kills them.