I'll sing the praises for the lowly Mossberg...lol
I had a few of the old 500's all thru the years growing up ...as did everybody.
Last summer, I also bought a Mossberg (Muddy Girl-pink camo version) SA20 for my DIL to start shooting a few sporting clays with my son and me, didn't want to break the bank open to see if she would like the sport.

She LOVES IT !
Like everything else I buy used, upon inspection, this little gun was pretty filthy inside when I got it...so I peeled it apart and scrubbed everything with Ed's Red...mag tube was BLACK with carbon and so was the gas cylinder...so I soaked the gas cylinder for an hour in it...put it back together and it works like a dam !
We've had only one stovepipe since July (from this... one box of old Federal ammo) and it's shot 125 rds every week, sometimes twice a week using almost all Challenger Target and a few boxes of Remington STS / Gun Clubs ! I clean the gun after every 2nd outing...theres some carbon but nothing like when we got it !!
Our local annual Hunters Education Course put on by the HWWA had 30 students registered this year...it has a couple of shotgun shooting stations as part of the course...I RO the rifle range part of the days events, and loaned my SA20 to the RO volunteers for one of the shotgun stations for the day. It smashed down rain ALL day! Kept me busy wiping the rifles off.
When the shotgun instructor delivered my gun back to me that evening, he said that little pink gun was the ONLY gun NOT to malfunction during the course of fire that day !!
.. 30 students, between 5 and 10 shots each, using # 7 1/2 Challenger Target loads, in the pouring rain !! I believe my OCD about caring for my guns certainly helped, but still, that was a pretty good compliment to get about the SA20.
I personally don't think you'll have any issues at all with those little guns..if you do a little bit of maintenance to em every now and then.
Most guys (almost all) at our club run the heavier handicap shells (3 dram) in their semi autos...don't matter if their Benelli's, Brownings or Beretta's !!
*** FYI *** The Weatherby's come with two gas cylinders ...one for target loads and one for Heavy hunting loads.
Best of luck with your decision...what ever it is !! ..cheers....Kevin