Do you know what version you had before the upgrade?
There is a setting in Web.config:
Did you previously have this customized? Maybe the new Web.config overwrote your settings? This setting really should not affect it but still might be related.
NText should be the correct data type for storing multi lingual text so it sounds correct for both tables.
I can't see any reason the HtmlContent module should behave any differently than the blog. I've reviewed the code and nothing jumps out at me.