Honestly, I would take it off... Not looking to start an argument, just saying what I would likely do if I were in his shoes.
Dagoof, is your mower a 3 pt. mount or mid mount? Do you ever carry anything on the 3 pt. hitch? If it's a 3 pt. mower, that could potentially make you tractor top-heavy if you were carrying an implement all the way raised while traveling on a side slope. But, not having a FEL gives your tractor a relatively low center of gravity. Removing the heavy steel ROPs will lower your center of gravity. And, having a mid-mount mower would actually increase your low center of gravity, making your tractor more stable.
I would say that your likelihood of rolling the tractor over is extremely low. As for mowing around trees, an acquaintance of mine got killed by his tractor while mowing around trees. Not having a ROPs would likely have saved his life. Gear drive tractor, he accidently got caught up in a branch at about neck-height. It lifted him off of the seat and pinned him against the ROPs. Old Kubota without a seat safety switch. Couldn't reach the clutch to disengage the drive. The outcome was not pretty and I won't discuss it in any more detail. But, if the tractor had not been fitted with a ROPs, the branch would've lifted him off of the seat and dropped him behind the tractor while it chugged away. I realize the outcome could potentially be just as bad for someone with a 3 pt. mower. Just something to consider, though.
So if you:
-Never carry anything high on the 3 pt hitch while traveling on a slope
-Have a mid mount mower
-Don't plan to install a FEL
-Only use the tractor on your land, which appears to be completely flat
-Insist upon mowing under trees (I don't blame you for wanting to do so)
Then, I'd remove the ROPs. My opinion.