I see you posted this a little while ago, make any decisions? I don't know much about the Gladiator, but I have researched some for the JL, as I've been thinking about replacing the MTs with ATs.
Like you I've been strongly considering that size (285/75/17), as it's the same width as Rubicon 285/70/17 take-offs (important cause of the narrower Sport axles and the offset on stock wheels, and no one complains about rubbing with the take-offs), but about a full inch taller/ and more sidewall (say vs a half inch shorter/but wider 295/70/17 33" where I think more rubbing has been reported). In my case, the Willys standard 255/75/17 M/T is an inch skinnier but only a half inch shorter than Rubicon take-offs -- not an especially enticing difference.
From what I read (also conflicting reports), it does help to have at least a Rubicon suspension / high-top fenders to minimize potential rubbing, but also how/where it rubs it's not likely a huge deal if it happens. The other potential complication I read about as you go bigger/heavier is not having the Rubicon gearing -- depends on the tire, but some of the lighter 285/75/17s might still be at least 7-10 more pounds per tire than take-off 285/70/17s, and definitely a lot more than what you currently have. Not insignificant when you do the conversion of unsprung to sprung weight to see what that equates to.
Not that I'm an expert, but since you're not off roading much it wouldn't sound like a huge deal to me. Are you planning on keeping your current wheels? One benefit to Rubicon take-offs and 285/70/17s are that they're a pretty good deal if you're planning on changing the wheel along with the tire. From the research I've done, if you're only changing the tire it's not nearly as great of a value proposition.
