Hi Dave
Yeah, it's a real bugbear of mine, generally it's the first thing I notice in a composition and I do not know why so many people post photos on various places such as non-photographic forums and sites like Redbubble, with way out of whack horizons.
Hopefully your blog will be discovered by many.
When I had my D200 I used the gridlines all the time, but still found the odd issue if I was not able to get right behind the camera - if I was in the middle of a creek standing on the same rock as the tripod and coming in from the side, for example - can be hard to judge in some circumstances.
PS takes good care of that with the ACR line tool when needed.
I see you're coming down
my way soon...
This is an hour's drive for me