The S100 is not available yet, so their is no real world information available.
It is typical of early reports on new cameras to be negative about something.
Seems to be a quirk in reviewers nature.
I suggest you wait for at least 6 months and then you will have some factual information.
That revue's main complaint is the S100 is slower than the S95.
That is probably because the reviewer did not read the User Manual carefully.
From what I have read, the S100 incorporated a feature from the G12 which was to do with automatically detecting which "Mode" to select.
That feature was to assist the less knowledgeable photographers.
As a DSLR user, you probably have never used a "Mode" because you have something better which is Shutter Priority, Aperture Priority, Program, and Full Manual.
On the G12 that feature caused a longer shutter lag. It added about 0.4 second to Shutter lag.
On the G12, you can disable that feature and you then have a very short shutter lag.
If you can get your hand on a S100 user manual, you can determine if that feature can be turned-off.
Regarding the Canon 300 HS:
That camera has a poor quality 24mm focal length lens.
Every picture (with no zoom) will be very soft on the right and left side of the picture.
The canon 310 HS fixed that by using a 28mm focal length lens.
But a DSLR user may find the overall picture to be softer than their DSLR pictures.
So do a little pixel peeping before you decide.
Also the 300/310 does not have Sutter Priority, Aperture Priority and Full Manual.
Someone having used a DSLR will find that to be a handicap.
i've been looking for a point & shoot to compliment my canon T3i. the S100 was what i was waiting for, but the reviews indicate still a few things canon didn't fix from the S95.