I ran spidertrax spacers on my 2013 JKUR on 37's and stock rims for over 60k miles with no problems. I torqued them down with red loctite to specs and they never budged. I checked them with a torque wrench set at 90 lb-ft (which was a little less than they were originally torqued to) every time the tires came off for any reason.
BUT, any time there was any vibration (wheel balancing) or anything odd, I worried about the spacers. In the back of head, I couldn't help with think that I was betting my life and my families life on 4 pieces of swiss cheese aluminum (10 holes in spacer; 5 for stock studs and 5 for the bolts that mount to wheel). I did it to save money and I liked the looks of the stock rims. Occasionally would read story of spacer coming off on the trail, although I never saw this happen. Probably because someone did not torque them properly or use loctite. Automotive shops did not like the spacers and I was always worried that some yahoo was going to snug them up with an impact wrench thinking that he was doing me a favor and break the loctite loose which might lead to them loosening up before next tire rotation.
Not doing spacers on the 392. The XR rims don't need them. I actually like the look of the non XR rims better, but instead of running stock rims with spacers, I would get this.....
These are a little wider and you can get them with the proper offset so they don't need spacers. One less thing to worry about. But it is more expensive than spacers. Having said all of that, however, if money was tight, or I was set on stock rims, I'd do spacers again and be diligent about torquing them down with loctite and checking them religiously. A little bit of mental anguish might be worth it. If it had bothered me much, I would've gotten rid of them and got new rims on the other Jeep.
Just my 2 cents.