Here I will give you my first impressions as it pertains to my purchase of 15 pair of Sergent Engineering couplers.
I knew about this product for a few years now but I have been reluctant to take the plunge. With permission from the boss, I placed an order for 15 pair of the couplers (5x6pack), an assembly jig and an uncoupling wand (absolutely nessesary).
The couplers themselves are diecast and have no flash. You get the feeling of quality the moment you open your first package. Then you realize that the couplers are small...they are scale....and they are a sight to behold!
Each coupler has 4 parts;
1. Upper coupler mold
2. Lower coupler mold
3. Knuckle
4. Ball bearing.

Assembly is easy, and only takes a few minutes a coupler. The assembly jig is a must. Assembled couplers are available, but 4 assembled couplers are the same price as 6 un-assembled. This version of the coupler is the Kadee compatable one...more on that later.
The magic is in the ball bearing. It drops (via gravity) and locks the knuckle closed. When it is brought up (via magnet wand), it unlocks the knuckle. Simple. We like simple.
Here are 2 comparative photos. The first Van has a Kadee-clone coupler and the second an SE coupler.


Note that these couplers lack a centering spring (just like the prototype) so the coupler has side to side slop.. That way, coupling on curves is no longer an issue, you just need to line up the knuckles.
Also note the open knuckle. Yes, you can now have an open knuckle. Try THAT with a Kadee or clone...fo-get-a-bout-it.
If you want to use the standard Kadee box, you need to file the neck of the coupler down ever-so-slightly to get it to not bind. Only a few swipes from a file will accomplish this.
To operate the coupler, you take these steps.



Notice the wire at the end of the uncoupling tool? That gives you leverage to open the knuckle when you apply the wand.
Finally, here is a short video (poor quality) that shows the couplers in action. Note that only ONE of the knuckles needs to be open for a handshake to occur. Both can be open as well.
http://www.youtube.com/watch?v=QdsIssp7I2g
I am excited by this product. Sure, you no longer can uncouple remotely, but remember that the prototype cannot as well.
Hope you enjoyed this review. If you have any questions, I would be happy to answer them.
David B