I’m with you and I’m not a physics major but I have had many lifts and I am very impressed with the 3.5 game changer on my JKU. It has fox shock which I am not a fan of but what I do like is it’s versatility in and off road.I have 40K on my Duroflex bushings. No wear. I checked them at 30K. Super easy to take apart and check too. No special tool, other than snap ring pliers and a hammer.
The springs, however, I have reservations. No personal experience with them, but the dual rate thing may look good on paper, but having half your spring collapsed at ride height doesn't make a lot of sense if you have your shocks set up proper.