Thanks for an informative debate / forum.
I mainly model HO US outline so have used Kadees for a long time.
For my '2 cents' here goes:
Free running is no good, you just end up chasing the car you want to couple to.
Light weight cars are no good, when nice and heavy cars have nice inertia.
Kadee clones in my opinion are poor substitutes.
In the thread the Kadee #4 got a mention. Clunky and all metal, but has a nice action, worth a try, just for the experience.
If you want to uncouple by hand you can straighten to trip pin and bend it until it's horizontal and parallel with the headstock. Useful for passenger cars (oops coaches).
Don't let them droop.
Get a Kadee set of drills and 2/56 tap. Useful to mount coupler boxes and for assembly stock (nice to be able to take things apart by just unscrewing)
The couplers benefit from a little fettling, removal of any flash etc.
I have moved to the Kadee semi-scale version for HO, so luckily have a source to cascade for my next venture into OO. (I think the smaller heads have a nicer action)
I think I will go for mounting boxes straight to the underneath of the wagon underframe (I have mostly Bachmann so seems easiest)
Regarding uncoupling I prefer 'drop down' magnets or the electromagnets (I have a phobia for un-solicited uncoupling)
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Has anyone mentioned the auto couplers tried out by BR (I might have missed a thread), I've seen pictures somewhere of them fitted to 16 ton minfits, the vacuum pipe coupled to the back of the cast steel coupling. Dowty rings a very feint bell.....
A lot of UIC freight stock (ferry wagons) have the capability of taking an automatic coupling, hence the drawhook being supported by a bolted on 'letter box' with a big void behind.
I will start a blog when new layout construction starts.
All the best
Ernie Puddick