Tamron 17-50 2.8 (non-VC) vs. Tamron 17-50 2.8 (VC)

Well, my friend is just testing my several years old Tamron, and she is very excited. She urges me to sell the lens to her, and buy new version

So - I am right now reading some reviews, trying to decide, if I should buy VC or non-VC version. My recent Tamron does not have VC, but it is true, that I shoot concerts too. But - I am also used to the sharpness of my recent Tamron. Reading following review I am not sure, if I would trade eventual softness with VC?

http://www.the-digital-picture.com/Reviews/Tamron-17-50mm-f-2.8-XR-Di-II-VC-Lens-Review.aspx

Petr