Hmmm. I just shot a picture of a tree this morning, looking up into a cloudy sky, right at sunrise. My son was actually the photographer this morning. I was helping him get the exposure and tripod setup properly.
Sky wasn't that bright. Enough ambient to see by comfortably. I exposed for the sky (get blinkies, then stop down slowly shoot, repeat, until they go away is my crude technique, but it works.) with a 4 second exposure at f16 and ISO 200 on my D3s.
When we went back inside for editing, we could bring the details of the tree out, but there was far too much noise to be acceptable, IMO. I was shooting and editing RAW NEF in lightroom 3. We tried luminance noise reduction, but it just wasn't good enough.
A shot like that would clearly benefit from your bracketing technique and exposure blending. So, 3 shot bracket, 1EV change, one blinking, one not. I can do that. I'm just going to have to try some different exposure blending software.