It's funny, I must have a high Nic tolerance, as I've smoked quite a few of the blends mentioned and have never been buzzed by them. Not that I wouldn't say they're not strong, I just haven't been buzzed by them. The only one I've not finished a bowl of was Five Brothers. Not because of the strength, but because of taste. I just didn't like it.
The last time I remember catching a buzz from pipe tobacco, was from a blend that I wouldn't normally call "strong".
It was early in the morning, I was fresh out of bed, I hadn't eaten and I was barely awake. The blend was McClelland's 221b Honeydew Flake, I guess the conditions were just right for a buzz.