Yeah, 6 Actual works, too, as does 'Six'... (it had a wonderful tendency to immediately focus the attentions of the junior Officer/NCO at the other end of the handset...)
The Mershons are/were essentially identical to the Pachmayrs, but I think Pachmayr improved the metal clip later in time.
Pachmayr also contracted the 'S&W'-marked versions for the N, K and J frames - the J framed version not being quite as common as one might think.
Most of the revolvers I've run across seemed to have Tylers.
I always liked the grip adapter idea - installed, the weapon's carry size is the same, while the custom wood stocks, or the wrap-around rubbers made the piece larger - not the best of ideas when you're carrying concealed, plus, the rubber versions want to 'catch' on the coat fabric - further illuminating the fact that you're strapped.
Now, if you're truly nostalgic about your older cop/gumshoe stuff - you 'need' a Mershon, and probably a Clark 'Sheriff' holster to complete that LAPD Robbery Homicide look.(cue 'Harlem Nocturne' and the rising cigarette smoke, with the crushed-out Camels in the ashtray next to the empty shot glass and lipstick-stained napkin...)
Now, that's the type of answer I expect from an officer
! I was a lowly Lance Corp., M.O.S 0331. '71-'73
Many years ago I read a review of the S&W Mod 38 or Mod 49 by LeRoy Thompson. He mentioned that adding aftermarket oversized stocks to small J and D frames increased bulk and therefore, increased the possibility of printing easier under clothing. He suggested mastering these small revolvers using the original stocks. They were designed for maximum concealment with a minimum grip that could control the cartridge it fired. I took this advice to heart. I practiced always with the tiny standard stocks to the point they didn't affect me adversely. A lot of range time with a weapon that has a grip you don't like, or a trigger pull you're not crazy about can be mitigated if you shoot that weapon a lot. You will get used to it and adapt to it's nuances. A target weapon is a completely different story.
When seasons and clothing permit, I carry much larger handguns than I do in very hot himid weather when I wear a lot less clothing and accordingly, carry small frame snubbys in Kramer front pocket holsters in cargo shorts. Unless I'm going into downtown Harrisburg or Philadelphia. I will opt for my plastic Glock 36 or my plastic Walther PPS, Glock 19, or HK USP CT 45., under an Hawaiian or loose fitting shirt for that scenario with a top quality IWB and gun belt. I care little about sweating all over my plastic pistols. A 1953 DS, is a different story! And, I hate shiny guns so anything but blackened stainless is a non starter. I haven't carried my SIGs in years and they are just combat finished carbon steel.
To me, the only viable grip adaptors are the Tylers and the old Mershon/Pachmayrs. As you mentioned, the only area they add size is between the back of the trigger guard and the front strap of the grip frame, no addition to size where it would be detrimental, like a longer grip frame, thicker backstrap, or a thicker grip width. Another plus for those who like to carry snubbys about 50 years old is that this type of grip adaptor enables you to keep the classic Colt or S&W wood stocks on the gun and they still look almost competely stock.
I realized years ago, I would never use rubber stocks for concealed carry. Rubber against any garment material might as welll be adhesive.