Gaming wise, yes those temps would be higher than normal. For rendering, its far better than mine are. That's to be expected though. Rendering uses 100% load including boost, and its not a synthetic 100% load like prime and such. I've had the jm series which reached 102c and throttled real bad while rendering. Swapped out for another same deal. Went through amazon instead of best buy next. Got a js model this time. First one gets to 99c-100c and sometimes throttles, not so bad or as bad as the jm was. New js model, cpu during prime/intel tuning gets 95-98c, dropped offset voltage -75 and run gpu fan full boar and get 90-93c. That's while rendering.
Difference between my js and your jx, is that your jx doesn't support intels integrated gpu, it relies wholely on the graphics card for pushing video. My graphcis card will run during games and programs if I set it, but its always using the integrated as well. We have come to believe a 10c difference between non integrated/non optimus enabled last years g750's and this years.
Seeing as how your under 90c, that's great. Yes it is warmer, but its full stress to the system. Gaming should be around 60-70c. Maybe a bit higher bepends on the game. But you wont see any throttling until you run 100c or higher. So you've still got room to spare. Also, better software would be hwinfo to run, and temps fluctuate, like 87 for a second then 89 then 84 ect ect. So sometimes temps shoot up high when you first start something, then the fans catch up and it drops. As long as its not bouncing around 100c there will be no negative effect.
You have a right to be paranoid. I have had 5 laptops now, and pretty much come to find out that it is what it is and that this thermal problem I thought I was having with this new series, isn't the individual laptops having a problem, its just the way these new ones run. Couldve saved myself a bunch of time, but im paranoid and if I spend $2000 on something I want ti to be 100%
