Basically, the RDS adds about a cubic inch. Bigger is easier to spot. Northern climates where people spend a good part of the year with layers of clothing... concealment is of course a bit easier.
It depends WHERE the added cubic inch is. A longer grip, such as moving from a G27 to a G19 is much more significant when it comes to printing / concealability. Ask me how I know.
I've been carrying for over 25 years. The optic is simply NOT an issue. As in ZERO effect on printing... because of WHERE the optic is added to the gun.
Dicken's story is indeed impressive. 40 yards. No optic on his G17. Here's a rendered representation (below) of what the shot looked like from his POV. The photo was taken at the same mall. What's not shown here is that Dicken steadied himself and the gun on a pole. He landed 8 out of 10 shots in the shooter. It lasted 15 seconds, not the two minutes originally reported. It was reported that the bad guys AR jammed. I wonder if he bought it from Jigs-R-Us and made it on his kitchen table!
Very impressive shooting. And it opened a lot of eyes, including my own when it comes to making the longer shots. Most of my practice is at "ordinary" self-defense distances. After the Dicken encounter, many of us tested ourselves. I passed, but not nearly as good as I'd like to be. And admittedly, my eyes can no longer focus on the front sight.
That's when I put an optic on my EDC. And then I
trained and practiced. A LOT.
A WHOLE LOT. I am now considerably faster with an optic than with irons.
I look for guns everywhere I go. It's pretty easy to detect who is carrying. It's not just printing. Sagging pants is another. But most telling is amateurs will favor the gun. Specifically, they unconsciously touch the gun all the time. Their hands constantly touching in that area. Another is habitually adjusting their clothes or feeling around to make sure their shirt hasn't ridden up and exposed the gun. Another tell is a lot of guys put a gun in the pocket of their cargo pants or shorts. The gun swings back and forth when they walk.
Most gun carriers simply refuse to get a GUN belt. It's quite odd. There is this MISconception that a "good thick belt" is adequate. They don't know what they don't know. Worse... they don't WANT to know.
A real GUN BELT is ESSENTIAL to concealed carry. There are no substitutes, because there is a HUGE difference between a gun belt and a "good thick belt." Whenever I talk to someone who wants to start carrying, I get the MOST resistance to the gun belt. For SOME reason, they just can't get past the false notion that a "good thick" belt is good enough.
I've been carrying for some 25 years. I just did the math... closer to 28 years. I've pocket carried (pocket holster is a MUST) - mine does not flop around.
I also carry IWB and OWB. I don't fiddle with my gun, because I know it is SECURED in a proper holster with a proper GUN belt.
But have I seen others carrying (ineffectively concealed)? For sure. Some are really bad.
I once had occasion to talk to a police officer about concealed carry in a private setting (in my work place). She was a narcotics team officer (and pro-2A). I was wearing dress slacks and a tucked in dress shirt. No jacket. I asked her,
"Can you tell if I'm carrying?" She looked me up and down.
"Look closely." I turned 360 degrees slowly. She said,
"No. I don't see anything."
I then told her I am about to do a "carry dump" on the counter. I wanted to let her know in advance.
"OK."
I then proceeded to unholster my Glock 27 from an IWB holster (tucked) at 4 o'clock. I removed the spare magazine (in a mag packer pouch) from my front left pocket. I emptied my right pocket, which contained a clipped Spyderco and a Swiss Army Super Tinker, along with a 2-oz cannister of Fox Labs pepper spray.
She flipped!
"Holy shit! That's amazing."