A search of GT archives will show much discussion on chamber empty versus loaded chamber carry, in terms of both the issues you mention: safety and tactics.
The empty chamber gun -- so long as the chamber really IS empty -- is of course less likely to be involved in an unintended discharge.
However, there are also shortcomings with this (Condition 3) type of carry when safety means, how fast can you get the gun up and running to defend yourself, in unpredictable circumstances when the other hand may not be available to rack the slide.
Personally, for a new shooter feeling insecure about basic firearms safety and committed to using an auto pistol, there is some rationale for condition 3 carry. Personally, I'd be going to a fully loaded revolver in that situation, and so long as the gun is mechanically drop-safe and in a holster that shields the trigger guard area, I carry my own semiautomatic pistols with a round in the chamber. If I had to use a borrowed auto pistol that wasn't drop safe, the empty chamber would start to make sense to me, personally. (I used the word "personally" so many times here, because that's what this decision is about, in the end.)
As always on the Internet...YMMV.