I have been experimenting with using the different types of couplers currently available, trying them out in various combinations on my rake of Ozrail's 4-wheel wagons. Most of the couplers on this rake are the standard knuckle type, either scavenged from the adjustable chassis packs or the spares supplied with each loco. There are never enough of these to go around, so I have now tried out both the pin-and-hole type and the permanently-coupled type from tgauge.com.
The pin-and-hole type do make it easier to couple up a train, but much less so than I would have expected. The small size and light weight of the wagons means that when fiddling with one wagon, its neighbours tend to lift off the track and promptly uncouple, so I have to go back and do them all over again. Any derailment or other problem also tends to scatter wagons to the four winds, and I find that life is easier when they stay attached to each other. The coupler pair is also physically bulkier than a standard pair, and this is quite visible in a mixed rake. I suspect that they might work better with bogie stock, but haven't tried this out. In the end, I have chosen to retire them from use.
The permanently coupled units are designed to replace a standard pair, and are the same size and have the same spacing as the standard type - they are visually indistinguishable. These have worked fine in all the test runs so far, and I am quite happy with them. I will be using them in fixed groups of 4-6 wagons with conventional couplers on the outer ends. Future purchases will be of this type.
A handful of my (black) standard couplers have longer shanks than the rest. This isn't documented anywhere, and I am not sure which model or pack they came from (comments anyone?). These proved to be very handy for the 3d locos, since they allowed me to compensate for body and chassis length mismatches, and the resulting bogie position issues.