I've used them for the the past 6 years or so and have been very pleased with them. They are the blue 14-18g versions.
We set up temporary Christmas layouts and I decided to make a reusable terminal "snake" of 5 equal lengths of 14g stranded for my main spine (about 20' long). That gives me my A,B,C,D and U terminals for my ZW. I then use the suitcase connectors to tap into those spines with 18g stranded feeders for all track and accessory connections. I use crimp connectors on the other end of the 18g feeders. Never had any issue.
The next year, once a track plan is determined, I unroll the snake, arrange it in the most efficient path under the track work and attempt to reuse as many of the existing feeders as I can. If needed, I add additional feeders using more suitcase connectors. If I don't use an existing feeder, I roll it neatly and apply a piece of electrical tape to the bare end connector.
I use a pair of ordinary channel-lock pliers to fasten the connectors and have never had any failures.
