Erik, with what I already mentioned, I owned used two AR-XAs in my systems early on in the hobby. More recently I restored two others for friends. When testing the restored versions I was surprised by the very good musical qualities they continued to offer. I would avoid the earliest 2-motor versions. Not saying they compete with $2K and up current arm/tables, but still decent and satisfying.
Regarding the AR arm, yes it is often criticized, so some have been replaced. The problem is it is not simple to modify the metal T-bar the arm mounts to, or the steel top cover if repositioning is required. But the original arm can be modified for some improvements. First off would be removing the damping pin. Then, particularly because of age, it can be rewired. One weakness is the plastic headshell (it is often broken plus does not allow for offset alignment). That can be addressed by replacing the entire arm tube/headshell. Possibly taking parts from an otherwise damaged Technics or similar.
Like so much in used audio, the main considerations may be condition and price of what you find between AR and Dual models.
