I've had a Souther for 25 years. It's been a love-hate relationship for all that time--setup, keeping it set up, all that. Recently, it's worked very well. But do keep the track clean with a dry Q-tip. Alcohol may melt the glue holding the track to the frame.
I did some mods on this arm--adding mass with sand, etc., all advised by Lou. I also bought a thing from ClearAudio many years ago that allowed the arm to rest on to posts rather than the spindle. That's hard to set up, but it made a huge difference on my Merrill table. Another issue is getting wire that works on the thing. Anything remotely stiff fails. The wire I got with the arm works well, but doesn't hold up. I'm using some Well-Tempered stuff, and Clear Audio mades something called superwire which I may try some day if I hang on to the arm. Also, I'd use the solid arm tube.
I disagree with the advice to use a Shure cartridge or any high compliance cart on it. In fact, Lou Souther told me that over time, he came to advise lower compliance. Years ago, I tried a couple of Shure V-15's on there. They were a nightmare. Did I have it set up poorly? I don't think so, but who can look back that far? All I know is that the Shure was a tracking mess. I use a Benz Ruby, which has a compliance of 15, and it does very well.
It's a good arm for clarity, wide soundstage, imaging. Not so great for muscle, texture, that kind of stuff. If I had money, I'd dump it for something pricey, but I've never pulled the trigger, so obviously it has its attractions.
I can't imagine it costing much now. Of course, this is a late response, and you've probably bought it or rejected it by now.