Originally posted by bizi Arpe, feel the same here. I didn't see this being discussed in the formal reviews that I read. It is an issue especially when the competition is compared to.
I also feel the SR is less effective on long zooms, and think about it, it makes sense giving the technology. Again I didn't do scientific test, and just a feeling based on the picture results.
Overall, SR as is is a valuable tool, but wish it could be improved to befit such a great camera. Optical SR is a main stream feature now(even on non-SLRs), and not many designs require such a delay.
Optical SR systems also have a delay. It is as noticable on a Canon as it is on a Pentax.
You should also note that optical systems are not available in all lenses. Take Canon for example, they do not have IS in their prime lenses. have a look and you will see how few lenses they have that are IS.
The other thing to remember is that SR does not replace good handholding technique. For SR to work its best, you need to take a moment to brace your arms to you body, control your breathing, and sqeeze the shutter. By the time you are set to take the photo, that is more then enough time for the SR mechanism to start up. This is also true of optical systems.
And finally, I can't think of any situation where I would need "Instant on SR". Most of the time, SR is used to add to the low light ability of the camera, because you are using a slow shutter. Maybe if you are trying to capture motion blur with a sharp background.
The only time that I fell optical systems clearly outperform body based systems is when I shoot film.