I dont use my PGO for "picking off cans at 40yds", though I have shot slugs and buckshot out to 25yds. No problem centerpunching the silouette target.
My PGO is intended for use at 10 to 20 FEET. It is kept in my house in an excellent hideyhole which will not a accomodate a full stock, or even a folder.
BTW, I tried several folders in my youth, and found I didnt like any of them. Some of the new one look interesting, but I just dont have the funds to expiriment like I used to.
The Mossberg OEM pistol grip is poorly designed, no doubt. I have also tried the Choate AR-style grip, which was even worse (it was on a friends PGO), and the Pachmayr Vindicator, which worked OK. But, after these trials, I have settled on the speedfeed birdshead style grip, which, unless you have tried it, you really cant comment on. It is far superior in recoil control and pointability. Shooting it is nearly identical in feel to a standard sporting shotgun fired from the hip. Plus it has the advatage of giving full normal access to the Mossberg top mounted safety.
My PGO is not my only shotgun, nor would I recommend that a PGO be ones only shotgun.
The shotgun is a tertiary weapon for me. A handgun would most likely be in my hand for a bump in the night, and I much prefer an M1 carbine for my HD longarm.
Again, if you are unwilling or unable to learn the proper technique to use a PGO, you shouldnt...you might hurt yourself, like the OP. But they are excellent close range weapons which have been used effectively since the days of the blunderbuss.