I've got a 19. I bought a G17 magazine with a grip extension for it. Really, the 19 grip is adequate down to the pinky and I didn't need that extension.
Concealing a handgun for me, has become much more about length of grip than the other things. I use a Kahr PM9 for most of my concealed carry. It came with a 7-round magazine with a grip extension, but my hanging pinky isn't any problem fro me at the range and it conceals a lot better.
I would think it is the same for the 26. I would shoot it without the Pierce extension and see if you can handle the haning pinky before adding an extension which just makes the grip stick out more. Like you say, then you might as well buy a G19.
.45acp, .40 S&W, 9mm, .38 Spl, .380 acp, 22lr
12 gauge, .223/5.56x45mm, 30-30 Winchester
2 Chron. 7:14 Christians must seek His face