I don't have any hands on experience with the Tamron....but as some people don't see the TDP's news:

http://www.the-digital-picture.com/N...aspx?News=4569

Also, I've found this to be useful:

https://www.thecamerastore.com/blog/...70-vc-shootout

My take, if you can get a good copy, it is a very nice lens, more than most of us need. But I'd be pretty concerned about getting a good copy and have a detailed testing plan if I were to buy one.