Hopefully this will shame Canon into matching their offering. There is however always the potential of a tradeoff between quality and image stabilization, not only because of the additional elements, but also because of the risk of decentering (this is afterall, what IS does). It's not that these issues are insurmountable in a fast zoom, the 70-200 f/2.8 IS II is a good example that it can be done, but as this lens shows there is a monetary price to be paid. Still, Canon 'L' lenses are supposed to be the best...