The Centennials will usually have a smoother DA trigger pull due to the fact that they don't have the hammer block safety that the DA/SA guns have, The Hammer rests on the rebound slide to prevent the hammer from moving forward untill the trigger is pulled, same as the DA/SAs as well..
The Centennials aren't "Hammerless" they have a Concealed hammer internally..
Also those 242/296 L Frame Centennials aka "Humpbacks" are a very different variant that S&W should reintroduce into thier carry lineup IMO..
They have a very smooth trigger that uses the standard K/L/N strut style hammer spring..
I love the Centennials but never said that I didn't like Bodygaurds, I've never owned one but that could change at any given moment.. The only Bodygaurd I have is my Lou Alessi shoulder Holster..

You Gotta love these great concealed carry revolvers..
S&W sells more 642s than any other handgun.
Looks like there's another batch of "No Lock" 642/442s in the mainstream & hopefully this will be a turn for "Change"
Which ever you choose, Or Both, Carry...Involk your 2nd ammendment rights..
Off To gunshow..
Gary/Hk