From a construction standpoint the White Hawk should outperform the JayFlight. However, my opinion is you should look at how you plan on using the trailer as there won't be a huge difference in thermal performance. But there is a pretty big difference in structural/functional performance. The White Hawk trailers are designed to be as light weight as possible. They have a sandwhich floor instead of 5/8" ply (2016 now has 5/8" ply), the water and holding tanks are smaller some by as much as 50% and finally the frame is a Norco NexGen which is essentially a bolt together frame. My family primarily camps in the national forest and once I reviewed all those items above I was fairly well convinced that the White Hawk would not hold up off road as well as the JayFlight.
The other thing to remember is these are not true 4 seasons trailers like an Arctic Fox. For there to be a substantial difference in thermal performance you need double pane, insulated windows, exterior access doors that are 1" thick etc.
2016 23MBH Elite
2014 F150 SCREW LB Ecoboost