JP rifles see more rounds, foul weather, and abuse than most "duty" guns. As long as you keep up on preventive maintenance and replace consumable parts at their recommended intervals (which is true for any gun) then they will just keep on chugging.
KAC and LMT make a premium but still "rack grade" combat rifle. The high cost is due to the innovation and R&D that goes into their products. They will also not have the fit and finish of a JP or Radian. JP and Radian will most likely tend to be slightly more accurate as well with stainless barrels rather than the hammer forged chrome lined barrels that come from KAC/LMT.
I'll disagree with the above poster who recommended KAC just because you'll be suppressed. There is nothing special about KAC rifles when it comes to suppressor compatibility aside from a slightly longer gas length and slightly smaller gas port than you would see on comparable rifles. Their sealed gas system with AN fittings will exhibit less leakage, but if you stick a conventionally designed can with a standard baffle stack on the end of a KAC (like a dead air sandman), you're not going to enjoy the experience. Ultimately the best thing you can do for ANY gas rifle is use a low back pressure can. There are numerous options on the market from KAC, Hux, B&T, CAT, Silencer Co, etc.
Based on everything you've written here, I would still steer you towards a JP. I haven't seen anything in your comments that would make me think the design philosophy of KAC is optimized towards your needs.
For what it's worth, I own multiples of all the rifles in discussion. I also compete fairly heavily in 2 gun, tactical matches, and run and gun matches. My rifles get dragged through mud, climb cliffs, swim across lakes, etc on the regular. My primary match rifles are KACs and they have placed me on many podiums and brought home a stack of trophies. But none of them are actually 1 MOA guns with factory ammo. And that's fine for my needs.