Terry,
I believe I owe you an apology. I stand corrected on both counts. Thank you for taking the time to educate me. I'm sorry to hear about your less than stellar business experience with McMillan, and that will influence where I spend my money in the future. I also want to clarify that I wasn't bashing the KMW system at all, in fact, I prefer it to McMillan's version. However, I assumed there would be a price and time difference that would not justify (for me) choosing the KMW over the McM. Clearly, I was wrong in that assumption.
I took the time to gather some pictures from my McM and KMW systems. Unfortunately, I don't believe I have the persuasion to get McMillan to send me a sample of their hardware, although I would indeed love to do a comparison in that sense. All I have are the systems installed. Sorry for the poor quality pictures, but it's getting late and I don't have time to set up a light box or edit the photos. I think this will work for educational purposes.
In all the pictures, the tan marble is a McMillan A5 with a McMillan clamp bar system. The coyote tan is a Manners T4A with KMW hardware. Both were installed by the respective stockmaker, although the paint on the McM's clamp bar system was done by me, which is why it is wearing off so badly. The McM has also been used significantly more. The first three pictures show the installed clamp bar area. They are quite similar in appearance and function (I suppose for the reason Terry mentioned earlier), but not identical.
Notice that the McMillan sits below flush, while the KMW sits flush. Of course, we can also see that the McMillan is thumb nut adjustable while the KMW uses an allen wrench. I don't believe it should be too difficult to convert either to the other. As an aside, the McMillan thumb nut is quite sharp and I've learned to avoid letting my arm rest on the area while carrying the rifle. The KMW has a longer slot, which seems to make the adjustments easier and tighter, although it's hard to tell since the adjustment methods are different. The KMW appears slightly beefier from the top view (the McM only goes until the slots, but they painted the entire area black, making it hard to see). Not apparent in the pictures is the depth of the clamping surface. The McMillan clamp is approximately .5" deep, while the KMW seems to be around 1". This means the KMW has approximately double the clamping surface as the McM. Take it for what it's worth, they both seem to lock tight for me.
The next picture is a shot of the underside of the actual cheekpiece. We see that the McM sits proud of the surface, which allows it to drop into the lowered cavity we discussed earlier. The KMW, again, sits flush (actually slightly below flush). The KMW has a very nice E-clip system to maintain the height adjustment and prevent accidental slipping if the screw works loose. This works very well. The McM comes with no such system. I added a drill stop to one of the posts (visible in the picture) which accomplishes the same thing. If my adjustment had been a little lower on the McM, I wouldn't have been able to use the drill stop as it would've been too thick. All in all, the KMW E-clip works far better.
The side-to-side adjustment on the KMW is accomplished by using an allen key to rotate the posts and loosen them. This allows the user to slide the posts in order to get the cheekpiece where he/she wants it. The only downside is that the cheekpiece must be removed to loosen/tighten the posts. I simply get the posts moderately tight, install the cheekpiece, make my adjustments, then tighten the posts again. Not a big deal, especially since I tend to run my cheekpiece mostly centered.
The side-to-side on the McM is accomplished through the top of the cheekpiece. This makes it easy to adjust, but leaves unsightly holes on the top of the cheekpiece. I don't care much, but some people might. I've never had a problem with the holes contacting my cheek.
We can see the side-to-side adjustment on the McMillan, as well as lack thereof required by the KMW.
And finally, what both look like installed. I won't say much on this, as it's mostly aesthetics. I prefer the more streamlined look of the KMW, though.
I should also note that I had issues getting the McM tight enough with the thumb nut originally. Greasing the threads fixed that issue. Both seem to be good quality, but the design of the KMW is more elegant and refined.
Well there you have it, Terry. My comparison of the two. I prefer the KMW overall. My main point previously was that they are both functional. I've had my McMillan for a long time and love it. But now knowing the price break down of the two, I would opt for the KMW for my next stock, hands down. Sorry to the OP for extended response, but hopefully some people will find the information useful.