sony or tamron 18-200?

Hi all,

Can anyone inform me on the quality of the Sony NEX 18-200mm F3.5-6.3 vs the Tamron version? My dealer tells me that both lenses come from the same factory, that the Tamron is a bit sharper (?), anyway some euro's less in price. Is there a comparison review on the web?
Regards,
Raoul