Those new ones look really bad to me.
Sure they’re much quicker to attach and adjust, but that’s about it IMO.
All of the load has to go thru one single point of contact now where the steel t-bolt is. On the old ones the stress from the load was well distributed over the entire length of the sliders. Now its all concentrated. I bet they wobble a lot, and will stress crack relatively quickly where the plastic meets that bolt.