I have the Canon 24-70 f2.8L II and I have not used the Tamron myself. But my wife needed a new walk around lens this summer, so we evaluated the Tamron and the new Canon 24-70 f4L IS.
As always I tend to trust Bryan at The-digital-picture.com. His reviews has consistently been in line with my own conclusions, when I have tried the products over time myself.
For the Tamron review, se below:http://www.the-digital-picture.com/Reviews/Tamron-24-70mm-f-2.8-Di-VC-USD-Lens-Review.aspx
I decided to go for the Canon 24-70mm f2.8L II, primarily because of its very fast and very accurate AF. I have had the lens since it was released and I have no bad images I believe I can blame the lens for. From what I have seen of examples, it also has the edge on bokeh.
I decided not to go for the Tamron for the reported inconsistencies in AF. This is pointed out by Bryan in the review above and it was confirmed to me by a friend who´s been using it for some time. He returned 2 lenses before he got a good one (he is very happy with Tamron customer service by the way), but he still gets the occasional (and very irritating) out of focus image, where he feels that it should have been good. Tamron´s EF compatibility is, as far as I know, based on reverse engineering and not licensing. That is a concern for me.
Based on what I have seen, the IQ of the Tamron is very good and I don´t believe I would be able to separate the two, unless the images was deliberately done at the known quality difference extremes. And I am not sure who would win. From that perspective I agree with the arguments used in the link you attached.
The VR is a very good argument for going for the Tamron. But for my use (there is always something moving), I am perfectly happy to skip IS on this lens. For my wife we ended up with the Canon 24-70 f4L IS. She lose one stop, IQ is great, it has a very impressive MFD and it is a very compact walk-around lens. The price is close to the Tamron.
The last reason I had for going for the Canon(s) is that I have owned (and still own) a lot of L-series lenses. I have not had any problem with any of them. I am willing to pay for consistent quality over time and Canon customer service (at least here in Norway) is excellent.