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

I'm thinking of purchasing the Tamron 17-50 2.8 (non-VC) or the Tamron 17-50 2.8 VC as an upgrade to my Canon 18-55 IS. Some reviews have suggested that the vibration control on the VC version isn't very good and that the IQ on the non-VC version is better. Does anyone have any experience using both lenses? Also given that the Tamron is faster across the focal range and two stops faster at the long end will I miss the lack of IS (VC) compared to my Canon 18-55 IS?