Note that all mainstream firearms with slide safeties (Berettas, S&Ws, Walthers, etc) are not actually intended to be carried with the safety on - they meant to be carried decocked/safety off. The manual safety is just an extra on the decocking mechanism that can offer safer storage and loading/unloading if you so choose to employ it.
So why does it matter?
it does on a carry gun imo...
because its far too easy to inadvertently activate the safety and/or be mistaken about its status.
im not talking about an AD/ND because you thought the saftey was on.
i dont have a problem with a decocker on the slide so much,but a safety is something i can definately do without(especially in that position).
its part of the reason why my 92 is a range gun(size and weight are major players as well though).
the fewer variables the better on a SD pistol.
i also prefer not having a hammer and two different trigger pulls on a carry gun...but i digress,thats for another thread.