I usually wear a 32-30 in pants, and for example, the 32 S in KUIU Attach Pants is my every day wear. I was in your position when preparing to order Chugach NX pants, so I ordered both an M and an S, thinking the M would be better, but wanting to try the S just in case the M was too long. The M fit, but to my surprise, the S fit even better, so I sent back the M and kept the S. It's a great fit if I'm wearing a base layer and Attack pants under, plus the stretch is a game-changer that allows closer fitting (which is nice for soft rain gear because then it doesn't catch on branches as much). If I were to wear a base layer and thick puffy pants, I might get some compression, but not too bad.
Can't go wrong ordering both and sending one back, imo, provided you have the short-term cash available until the refund clears.