I love the grips. They look and FEEL fantastic. They fit very well, but they don't necessarily go on easy. I tackled the CS9D first and that may have been an unlucky accident.
There are a couple of tricks to learn in order to get them slid on the first time but the real problem was that my pin holes didn't line up well. (the pin holes were well undersize on both sets so keep a small, fine, round file handy) The holes in the grip were low(and I now suspect that it was the entire grip riding low), but my fix was to file out the ID of the holes cheating upward. It eventually worked, but I believe a better fix would have been to relieve the inletting if I could have figured where it was first hitting the frame. I enlarged the holes only enough that the crosspin would be a tight fit and that was BAD. Once I got the pin started into the right side it eventually broke out a small chip as it emerged on the left side. I stopped before the chip detached and drove the pin back out. Made a few more adjustments(including breaking the inner edges of both holes which I'm sure helped a lot)and drove the pin back in through the left(damaged)side and all was well.
The CS9D grip has a lovely Coke bottle shape to it and it's hugely comfortable. Probably about as wide as the Hogues that it replaced, but wasp wasted through the web so it 'feels' much thinner. The checkering is very sharp and 'grippy'. Except for the fitment issues I had I'd say they are perfect and I think I know enough now to avoid the worst of the fitting if it comes up again. My set had a very narrow slot for the hammer strut that was preventing the grip positioning early on but a couple of swipes with the file cleared that up. Still needed to partially depress the trigger for everything to pop into place, but the 3954 grip didn't show any of these problems.
Total time spent fussing with the CS9 grip was a very frustrating two hours and I still didn't get it done completely without damage. I'm fairly advanced as a hobbyist,..........if you're not you'd better hope for fewer problems up front. I suspect that I'd be paying a gunsmith 2 hours shop rate for fitting these grips and I'd never get him to fit another set. OTOH, the 3954 grip went on simple as pie.
The 3954 grip also had the undesize pin holes but those filed out in a couple of minutes and again I broke the inner edges to avoid the chipping problem I had with the CS9. The grip fit up higher on the frame without any work and the holes lined up perfectly. The slot for the hammer strut was twice the width of the CS9 grip so there was never an issue there. I did get to do the three-handed juggling act while trying to get the grips lined up with the frame holes all while pushing the plastic block in against the mainspring pressure, but it's no different than any other grip that uses the Hogue style block. The real problem is that you're doing this while trying not to blast a chip of wood out the exit side. With the Hogue block all you're working with is the frame and plastic block. The wood grips go on separately with screws after all the cursing is finished. Forgot to mention,..........the plastic block was extremely tight in the CS9 frame and had to be driven into place. The 3954 block fit much better in the frame but that's good and bad. At least the CS9 block stayed put once the holes were aligned, even against the mainspring pressure. The looser 3954 block became another key variable in getting everything assembled.
The 3954 grip is identical in size and shape to the OEM S&W Delrin grip and again the sharp checkering is very 'grippy'. If you like the original straight backed S&W grip you'll love the KSG. I much prefer some sort of arched grip(but still love the KSG). What I liked best about the 3954 grip is that it didn't fight me every inch of the way. 15 minutes tops and it was finished. Both grips fit tight to the frame and there is no movement and they both look and feel fantastic.
Not much comparison to do on the 39xx grips,...........same size and shape as original. The CS9 grips are more shapely than the OEM Hogue rubber grips that the pistol comes with from the factory and thus they feel slimmer. They'd be larger than custom fitted 'Big Dog' grips obviously, but I think the KSG CS9 grips are the pick of the litter. They've taken me from not really liking the CS9 to loving it. I have a picture here comparing the three,........KSG CS9/3953 smooth wood Hogue/KSG 3954. The smooth Hogues make the 3953 feel like a little double-stack. The KSG grips maintain the 'small gun' feel of these tiny single-stacks.
BTW, I made a remark somewhere upthread about stock pictures in the auctions,.......at least in these two instances I received the exact same grips as were pictured. Both are nice; the 3954 particularly so. That one has a bit of contrast mineral streaking and some flash in the web,........very nice.