I have multiple pairs, and am quite depressed they discontinued the fullseats. The “slim secret” is simply that the woven, non-stretchy pocket material extends from the pockets to the fly, if you halfway engage your core muscles you suck it in more than the breeches help.
They just fit me like they were made for me, and I’m a little bit “hippy” and my 32Ls are perfect. They’re one of the few styles where the “L” is almost all in the leg and the waist isn’t hovering somewhere in the vicinity of my bra band. I like the material around the calf, it’s snug without being restrictive for me. I also like that the fullseat is lined with the wicking material. I don’t understand fullseats where the seat material is unlined right on your skin. It just rubs and feels nasty.
I guess I’m lucky I’m not riding much, they’ll keep until such time as I’m riding more down the road.