Insets and extrusions on curved surfaces in subdivision modeling is notoriously hard to do because the support loops will break the equidistance and cause things like pinching. When doing a shape like this you are much better off getting the shape right, and then subdivide and do the inset last. From left to right.…
STEPS FOR THE NEW ONE. 1. box 2. inset the sides i want to bevel, top, left and right 3. use turbosmooth and smoothjing groups (top left and right have the same smoothing groups 4. delete the edges inbetween those sides. 5. Bridge and turbosmooth. And i bet you Perna will do it in 5 steps less.