I read comments from people who do not like the slide mounted safety on the Beretta 92. What makes the frame mounted safety more preferable?
Sorry I didn't catch this sooner and if someone else already addressed this the same way I'm going to, double apologies.
There are many things that go into making something preferable or not. Design, location, mechanical operation, hand size/strength, or even just past experience.
The Remington 970 and the Mossberg 500 shotguns are practically identical. But the safeties are different. The Remington's safety is a button on the back of the trigger guard while the Mossberg's is on top of the shotgun, just forward of the stock.
While the Mossberg's safety location and operation makes it inherently ambidextrious by thumb operation, the Remington's standard safety is NOT, being operated by the finger of the shooting hand for a right handed individual. And it's not a simple matter of just flipping the safety button around.
Location, and physical operation, determines what digits are required to operate the safety, how much force is required to operate it, how easy it is to reach without significantly altering one's grip, etc.
A frame mounted safety us typically UP for the SAFE position and DOWN for the FIRE position. The slide mounted safety on the Beretta is DOWN for SAFE and UP for FIRE. Opposite directions.
The direction a safety is operated is important for more than just "what you're used to". Operating a safety requires different muscles to be utilized for the down and the up directions. In general, these muscles are more powerful in the "down" direction because this is the direction the thumbs move whenever we grip things. We apply more force gripping than releasing and pulling the thumb up. So, in general, it's easier to pull something down with the thumb than it is to lift something up with the thumb.
A frame mounted safety typically puts the safety right next to the thumb which operates it...sometimes even in contact with it. The slide mounted safety requires moving the thumb quite a distance to even reach the safety in the first place.
Also, a frame mounted safety on the Beretta 92 does not have a decocking feature like the slide mounted safety. This is part of the "design" function difference I mentioned earlier. The frame mounted safety essentially works to block or otherwise inhibit some action from taking place when you attempt to pull the trigger. This means the frame mounted safety typically requires less force to operate to perform that mechanical function (though significant force may still be required depending on detent depth, shape, and spring tension).
The slide mounted safety, however, must operate the decocking mechanism which drops the hammer (and prevents the firing pin from being struck). This inherently requires a bit more force to operate just to perform this function.
And, of course, one cannot ignore personal preference, however much some may poo-poo this. If you are used to frame mounted safeties because this is what the majority of your experience revolves around, then it's only natural that you would prefer a frame mounted safety, if only for its familiarity. Some may prefer them for simple esthetics, as well (they just like the look of it in that location). That's perfectly OK, too.
My advice to you, or anybody else, is to handle both and see how it feels to you.
I own several pistols, one of which is a Beretta 92FS which has a slide mounted safety/decocker. I bought the Beretta simply because I've always loved the look and feel of it. It's a beautiful gun and fun/accurate to shoot. The safety, however, is not something I would prefer for a carry piece. I prefer a slide mounted safety, consistent with most other pistols I own.
This is simply my preference...which should not be used to gainsay your own. I certainly will not consider getting rid of my Beretta for this, though. I love a beautiful gun, even so.