I use keels in the Bean Bags; I think this counteracts the short feeling. I tried a shaper personal 5'6". Went great in very bumpy small trade swell, but felt kind of short with the fins I had (no keels/no big twin).
For people who either ride their shortboard or don't surf, and refuse to surf any wave without a pocket, I'd ask the local shaper to take said shortboard, shorten it an inch or two, bump the width, and relax the rocker. Don't go straight to a mini-sim, then say it sucks in shorebreak wedges.
The 'I paddle in fine, pop up, and I pump but nothing happens' I would blame rocker, especially tail rocker.
Waist with plus sets but PUNCHY, and basically anyone who wants their shortboard to be a little easier to ride, I would suggest the OG Lost Rocket. Redux or 2/3 might be good too; haven't ridden them. But the OG Rocket, it gets in that little bit earlier, little bit faster, but all that flip in the tail makes it feel great in steep stuff where drivier boards don't fit and start to feel like a handful.