I have a mossberg 535 and several barrels for it meant for a 500. I am fairly certain that the limited selection of 535 barrels are all chambered for 3.5inch and under, whereas the 500 barrels max out at 3 inch rounds.
The barrel that came with my 535 is a deer slugger, it is rifled. This in itself makes the barrel a poor choice for home defense, or goose hunting as it disturbs the shot pattern to a slight donut.
Putting a 500 barrel on a 535 is no small task. Regardless of what derivatives Mossberg makes, a 500 barrel will need a 1.1x1.1 standoff (plus threads tapped in and die'd out, 7/16-20) to mate onto the 535's slightly *shorter* magazine tube. The threads on the 535 and 500 are the same at the nut. The magazine tubes are interchangeable to allow either choice of barrels, however most 500 receivers will likely not cylcle 3.5 inch shells properly (not that anyone is posting about converting in that direction).
I agree that the brownells kit is a much smarter choice IF you do not plan to use other barrels. Conversely, it actually makes more sense to have a few shotguns than to have a few barrels, with the small difference in price so those suggesting a mav88 are thinking ahead.
For me, I like the adapter I machined that allows me to put a 500 barrel for muzzle loading, or a HD 18.5 cylinder bore (3in max) on my 535. Converting my magazine would make my useless deer barrel uselessER. Lesson learned here, Buy what you need, not what is on sale (or know what you need, I did not at first).
PS
the referenced image comparing the 500 to the 535 seems NOT TO SCALE or possible named in reversed. Fact of the matter, is the 535 magazine tube sticks out less far than the 500, period.
PSS
heed chamber overpressure warning!!! Never fire a shell longer than what is stamped on the barrel!!!