Only time will tell and getting a lot of them in use to produce a decent sample. The manufacturers will not talk about failure rates, so we have to depend on forums like this to provide some feedback.
Chris
Not only forums like this but across the entire trailer spectrum which is a better indicator and more importantly for the OP with a heavy trailer is from other folks experiences with heavy trailers.
One poster here pushing the new Carlisle tires only experience with several trailers all under 5500 lbs. So sure any ST brand will work for him.
If a poster with a heavy trailer is looking for answers to his tire issues he sure wouldn't post his question in the pop up section.
Trailering forums (any type) are a better bet for separating a tire mfg PR or a tire chain PR flowery fluf from what has worked the best and what still doesn't.
IMO the cap under the tread was a good move for Carlisle. Any thing should help a poorly made tire.
However Goodyear added the cap, with other changes not specified, to the Marathons back in the early '00s. These then new tires had a circle S embossed in the tires sidewall. Most folks found they worked much better on light weight trailers but anything over 7k/8k and lots interstate speeds didn't work for many.