No experience with these in TRs, but it is a big issue in the early Porsche community. Rubber bushings work by bending, but the delrin ones must slide, in a joint that is not designed for that. The result has been wear and loud squeaking--enough to drive the user nuts, and a noticeable difference in the ride. Greasing them helps, but not for long. Dunno if this is an issue in TRs, but after listening to many negative reviews, I've never been interested in installing them, in any car.
I return to the old aerospace industry saying: "better" is the enemy of "good enough."