I prefer a stiff leather belt for a pistol of that weight. The Wilderness belt works well with lighter guns though...more my summer time rig. Just my two cents.
I wear a 1.75" wide Wilderness belt every day. Mine has the CSM insert. The newer belts made by Wilderness aren't as good as the ones made 3 or 4 years ago (when I bought my first one).
I would go with the CSM if I were you. It's "sufficient" in it's stiffness. I actually wish it were a little more stiff. If the 5 stitch isn't as stiff as the CSM, you're gonna have some tilting and sagging goin' on.
I have a couple of Wilderness 5 stitch. I love them and wear them most of the time. I really like how adjustable they are. That being said they are not nearly as stiff as my Beltman leather. I carry a 3" 1911 which probably weighs close to the 5 due to the bull barrel. It works just fine but the leather is a bit better due to stiffness.
I have had the wilderness cms for a few month's now, and its a great belt I carry a g23 with a tlr-1 and a 3" 1911. It holds the wight very well. Good luck with your search.