Shelter 501 mkii then what now

I bought a Shelter 501 mk ii around 10 years ago and most folks on Agon then thought it was the best value cartridge of its time. what is the current around thousand dollar cartridge champion
well you know I was thinking of getting a retip from
soundsmith can anyone tell me what I might expect in the
way of improvements with the ruby upgrade thanks for you
help so far
If it needs re-tipping you really have nothing to lose. You end up with a great sounding cartridge for $250 - $350. It sounds different, but not necessarily better or worse. Hard for me to describe with the passing of time since I have heard it.
tracking ability improves drastically to the point of producing substantially less surface noise. Ruby rings substantially less and has less resonance vs. aluminium or boron.
I've no doubt that 901 may sound better, but you won't loose a dime if you just upgrade current.
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I have only used a SS Level 2 stylus on my 501 since buying it used: under a microscope it the original stylus showed a lot of wear and the seller kindly and immediately paid for a retip. Pretty cool.

So: the Level 2 is revelatory for me, particularly against the elliptical styli Shelter likes to use. It simply gets into areas of the groove that haven't been played before, and reawakens a lot of older records I'd written off. I really am an adherent of the Level 2 upgrade because its profile isn't as severe and difficult to line up as the Shibata Level 3 tip. Hope this helps.
I talked to Andy Kim and he told me the micro line stylus with the Boron cantilever would make it better than a 901 improve the sound more than $100,000 amp so this is the the way I'm headed I'll keep you all informed
What is the original cantilever? (Aluminum, boron, or Ruby/sapphire?). And what is the shape of the OEM stylus? Thx.
I had a 501 re-tipped at SoundSmith with the OCR.  It was fine.  But it was easy to tell that an Audio Technica Art-9 outperformed it.  The re-tipped 501 was easy to sell.
I do not believe in re tipping. If you want it remanufactured send it back to Shelter. The Clearaudio Essence MC and the Audio Technic AT ART9 are both excellent trackers and solid sonic performers. I have never listened to the Shelter so I can not compare but to get significantly better performers than these you would have to spend 3-4 times as much.
"I do not believe in re tipping."

I can assure it’s a real thing.

Sorry, the temptation was too great....

Anyway, retipping/rebuilding by a third party is just as good as a rebuild by the manufacturer as long as said party knows their stuff. It simply depends on whether you want/need the cartridge to sound the same when it returns, or if you’re happy with one that sounds somewhat different but most likely equally good.

I’ve had both done, but likely won’t ever go with a manufacturer rebuild ever again, simply because the wait is usually waaaaay longer than when using a third party. Benz Micro in particular has been particularly tardy in my experience. Besides, making use of a trade-in option is often only marginally more expensive and you don’t need to wait for months on end for your cartridge to be returned.

However, third parties like Soundsmith saves both time and large chunks of money and the results have invariably been excellent in my case.
I've had retips done by both Andy Kim and Soundsmith.  I was happy with both, but liked using Andy a little better because he was local (at the time) and got the job done pretty quickly.  Perhaps if I had a new copy of the same cartridge with the stock cantilever and the retip to compare I may have noticed some differences in sound quality, but I did not and I was happy with the way they sounded. 

I've also had Van Den Hul retip and rebuild the suspension in one of my cartridges and was very happy with the results.  It did take a looooooooong time, but it was rebuilt by AJ Van Den Hul himself.  How cool is that?  I bought that cartridge used and when it arrived there was no diamond on the stylus, so I never got to hear how it sounded "before".  The seller gave me a full refund and it cost about the same as I paid for the retip/rebuild, so it all turned out well.
Audio Technica ART7, if your phono stage has sufficient gain for about 0.2 or 0.25mV cartridge output. It’s technologically advanced beyond the ART9 (because it uses amorphous core coils and ART9 does not), yet costs a bit less. Can be had for ~$800/$900 brand new.
And, I don't pray to the great re-tipper in the sky, but I believe in him.
Years ago I tried the Shelter 501 mk ii based on reviews and comments in Audio forums.  At the time the cost was a real leap. I felt it was a big waste of money and sold it after a few months.  Looking back I felt it had cost vs performance issues. It was not worth the cost for what I got.  Since then, I don't spend more than $500.00 +/- on cartridges and stick with AT, Denon or Ortofon.