I'm in the process of slowly modifying my Thorens TD145 and I want to change out the stock tonearm prior to upgrading to a Miyajima Premium BE Mono cartridge. The obvious choice would be to consider a lightweight SME, possibly the entry level magnesium SME but honestly, I haven't yet looked into that much. My local audio guy showed me one of his Clearaudio tables and mentioned that I could put that entry level Clearaudio tonearm on my Thorens but that I would need to either set it on a wall mount or as I was thinking, suspend it from the ceiling. The notion that I have at this point is to move in the direction of a lighter weight tonearm than what is on there now. This may or may not be of use to the question that you pose however, I wouldn't mind piggy backing on your thread as I need to learn about this same general topic.
Thorens TD146/160 with Ortofon 309 arm?
One of my friends have Thorens TD124 with Ortofon 309 arm (ORTOFON RMG-309?) and they looked to be a very good match. He suggested me to have Garrard 301 with Ortofon 309 arm, but they would cost me $3~4K. I have TD146 mkii and wonder whether it would a good match with with the Ortofon arm. Maybe the arm is too much for the (cheap) turntable?