Low profile side wall and big wheels most likely causing stiff ride sensation, I read quite a few reviews on wheel/tyre combos before I purchased my 500x as roads here in Scotland have pretty poor wearing surfaces.
I had an 500x on demo for a week recently.
It came with 41psi in 3 tyres and 36 in the other one. I set this to 41 as well. I didn't find the ride too hard or bouncy and also the "noisy" engine didn't bother me.
Have the suspension settings been retuned since the 500X first came out?