Yes, Iwien that is me.
I purchased 2 chromium crushers a 2.5" and a 3". Gave the 2.5" grinder away. Guess I've had the 3" grinder now for about 6 weeks (?) or so. It does a great job of grinding, no doubt about it. The one issue I had was a few weeks ago when I was cleaning out the bottom compartment where the kief collects. I happened to be upstairs, by a window, when doing this and the sun light was shining brightly thru the window. Noticed something "shiny" in the kief, looked with a magnifying glass and found small pieces of metal!! Using a magnet, I collected about 6 small pieces of metal, which were from the screen, not the grinder itself. Had cleaned the grinder really well before using, so very surprised to find pieces of metal. Wasn't going to use it again, but decided to clean it again and use a strong magnet to go over the screen. No sign of any metal pieces since then, so I've been using it a lot. I do own a MNB grinder also.
One thing to point out about some of the 4 or 5 piece grinders (at least CC and MNB), you can assemble them so that they work more or less like a standard 2 piece grinder. With my 3" CC and the MNB, I can simple remove the section that houses the screen and screw the remaining pieces together. Looks just like the 3" CC that stonemonkey listed earlier. There is the (1) top piece with the teeth, (2) the second piece with teeth and the holes and (3) the collection piece at the bottom (hope that makes sense). When I do this, I remove the layer with the screen, reassemble, add the herb and grind. With no screen, obviously you can't collect kief. But if I turn the grinder upside down, I can grind away and nothing falls thru the holes. After grinding for a while, simply turn the grinder back over, couple of turns and it all falls thru the holes into the collection area. (hope you can visualize that)
What I like about this option is I can collect kief if I like or remove the one section with the screen and use it more as a standard 2 piece grinder. So if you don't want to buy different grinders for different applications, think this is a possible alternative. Sure, may not be the best alternative but one to consider.
Forgot the question about the magnet in the top of the grinder. The CC has a very strong magnet. Can easily pick up the entire grinder by holding only the top. Compared the the CC, the MNB grinder has much weaker magnets. I actually like the feel of the MNB grinder over the CC, but the 5 piece MNB is not very well designed IMO. The screens are not permanent like the CC, so you have to deal with screens that move some and that creates problems for me. I can, and do, remove the screens on the MNB grinder, reassemble the grinder and use it like a standard 2 piece as well. Why? Smaller holes than on the 3" CC, so I can get a finer grind.
Yes, with the 4 piece CC, the screen is located directly below the section with the holes. Grind away and everything falls thru the holes and "sits" on top of the next layer that is the screen. Below the screen is the kief collector. Hope I answered all the questions.
of course imho most of the time I take all the pollen out of my ''aerospace'' grinder and pass it thru one of my payload bag screen to remove all nasty green pieces 
. Now I'm really confused. Thanks songa..........lol.