I bought a 2nd hand IR from ebay. It was a bit sticky, not very slick movement. Strip down showed the brass guides had been damaged from over extension, probably due to over pressuring the air return, which was probably due to the stiction in the mucky seals. A rebuild kit from spesh was easy to fit and it’s now working as new*. That DIY rebuildability was a key feature for me. Routine DIY cleaning / servicing (which is easy enough) should prevent the issue occurring again. If they did a 27.2 version I’d have one for my HT too.
* there is a little rotation in the post, about 3mm at saddle nose, but comparing this to a new one on a shop fresh Camber it seems to be standard.