I tried the coiled wire on my previous travel trailer when the original factory one literally frayed in half (I suppose from movement all the time).
I did not like the coiled one at all. It had to be stretched out almost to it's max to reach the truck bumper and the break-away switch on the trailer. It was causing so much tension, the pin on the break-away device on the tongue would pull out on it's own, and the vehicle was not even moving.
I very quickly discarded that one and went back to the uncoiled type. Never had a problem again.
Now that I have a 5er, I'm still not completely satisfied where that cable should attach to. I've tried different spots, all work well I suppose, but I've carefully considered objects moving around in the bed of the tuck hitting it too. I think that's why I'm still looking for the best solution.
I do have the carabinieri D ring. I've been using it on all my trailer break-away cables for years now. I never did like the way it came from the dealer all snaked through the TT safety chains and attached to the chain hooks. Never figured out why they did that, except to keep it from tangling... but that the dealer for you, you know.
At the walk through for my current 5er, he told me the brake-away cable needed to pull the pin before the 5er hitch actually passed the distance of the end of the truck bed. He SAID,.... most people hook them in the corner front hooks in the bed of the truck. Mine did not reach that far unless I add an extension. But then, that means the cable is vulnerable to anything moving in the back of the truck, even if the cable is in a sleeve. If anything bumped it, even in a sleeve, it doesn't take much to pull the pin, because we tested that too. And the brakes DID lock up REAL good!
Anyway, thanks for the post and this reminder. The 5er appears to be a bit more vulnerable to this happening than the TT's ever did, for obvious reasons of course. I have 3 weeks to figure something out before our next road trip for a week.
Thanks!