There's still the grip angle of the shockwave, and smaller top-to-bottom dimension compared to a "common" scattergun pistol grip, that I find appealing.
I've shot a tube of #8 and 00 through a PGO Persuader, and it didn't feel all that good - but hip-firing (I know, I know... I was 18 and had never fired a real gun before that day) a standard stock was much more comfortable.
All I'm saying is that overall length is important, but width (such as a carry pistol) and height shouldn't be disregarded. A PGO shotgun with a slim and narrow profile has its uses and I'm just wondering if even if my state won't allow a <18" barrel, the Shockwave grip still has merit, limited though that merit may be.