The only Pioneer that has a (stronger) ROPS is the 6. The wall thickness is identicle on the 3 & 5 . The 5 is about 300 lbs heavier than the 3, has less ground clearance, and a taller Cg.It's not about using them all the time. Its about having them IF you need them.
Mud & dirt in bed? Use a bed liner. Less than $100 to eliminate that problem completely.
Then there is the full (stronger) ROPS cage.
Then there is the full roof to keep both passengers and gear dry.
Then there is resale value.
Those are just some of the reasons the 1000-5 is vastly more popular than the 1000-3.
Just sayin.
The 5s extended roof might be of benefit in foul weather for keeping gear drier, but a tarp works too. I think the 5 has its place but it's ammenities are under used by most. But its nice to have a choice.