I just got a pair of these the other day. They are my 6th pair of IH jeans. I normally wear a pair of 461 (no S) and a couple pair of 6461Z (for work). These are really similar to those with the biggest difference being the rear rise. The fit is perfect for me! That higher rear rise keeps my boxer shorts from getting all jacked up. I normally have to make sure the band on them is below the band on my jeans or else they start moving up. I am 6'2" and about 145lb and went with the tag 32 measuring 32". My worn in pair, generally about 33" and I can fit into 32 Dickies which measure exactly 32". So, the fit is snug, but not too tight. And when they stretch a little, they will still be really good.
This is also the first time I have had the standard 21oz selvedge denim. I know that sounds kind of crazy but I have the superblack no fade 21oz, standard non-selvedge treated 21oz, and 25oz (and a pair if TW634S in 14oz). This 21oz selvedge feels broken in already compared to the others! It's so soft. Compared to the non-S 21oz, it is a little bit lighter indigo and feels a lot more textured. The weft being more cream colored gives them a different look also compared to the non-S. The non-S almost has a certain sheen to it. It feels really smooth and slick. The selvedge lays real nice right out of the package where the non-S took a long while to really break in and become soft (I know that being stiff was the purpose of the treated non-S 21oz though).
Overall, I love all the different denims in their own way. I can, however, see why the selvedge 21oz has become the standard, flagship denim.