Great Thread. I just purchased the 24-70II and I have the 24-105, I was wondering the same question.
I don't think I would need IS for general walk around use and still be able to produce sharp images. Anyone care to shed light on this?
If you read form the beginning of the thread you'll find some interesting comments and observations.
The 24-70II is a superlative lens; the best there is optically, and I can well understand people who have purchased it ditching the 24-105. But the former doesn't have IS and it depend on how much you value this. Over the years I have come to realise that I need IS.
Here's a shot that has made me a fair bit of dosh. I was shooting at the school, thought the evening light was a wash out, then literally five minutes before sun set the sun began to break through. I ran down the hill with the 5D and 24-105, waited briefly to get my breath back and then began shooting the sequence at 1/30s because I needed through DoF and low ISO (100 ). There was no time to take or set up the tripod. I've included a 100% crop which is straight of camera, converted and un sharp mask of 100% 0.3 pixel as I have sharpening set to zero for these shots. The final image is sharp enough to be blown up to 3 metres across and is on display at the school. We sell smaller ones 1 metre across the the 'old' boys and girls of the school.
Without IS this shot would not exist.