I have two problems with the "suitcase" connectors:
The wider the disparity of wire size the harder it is to both find the right size connector and get a good crimp on both wires. They do make some that work with a 12ga bus and a 20ga feeder, but they are hard to find. I find with that set of wires in them the 20ga often does not get properly displaced.
To a lesser degree the metal bit can turn cutting a good number of the strands in the 12ga bus wire which I feel defeats the purpose.
If you want to use Insulation Displacement Connectors then the T shaped ones are better. They fold over the 12ga bus and give you a screw or spade terminal to connect the feeder. It resolves the disparity of wire size issue. Another tact would be to use a 12ga - 16ga suitcase, a short 16 ga feeder off the bus to a screw terminal, and then break out to 20ga feeders.
Nothing wrong with using the IDC's, for sure, when done properly. I just find it easier to spin the xacto, cut the insulation, solder real fast (iron as high as it will go, in and out it's all copper) and tape it up. Plus I know there is
no chance it will vibrate loose when transporting modules around.
Not to mention, cheaper, no parts to buy!
