TT, 12" Tonearm. Who tried and ended up preferring 12" arm?

@elliotbnewcombjr I run 12" and 9" Jelco 850 on the same table. (I’ve also got two 12" 750s.) The 12" is better. It’s more open and dimensional. If you are going for the GEM, get the 850L 12". It is so much better than the 550/750. I’ve not heard the 950.

P.S. Stay with the Jelco magnesium headshell. You won't need anti-skating on the 12" although YMMV. You'll need phono cables. The Jelco 501 is perfectly good. Don't be tempted to replace it.

Thanks for the advice.

So, up from 850L tonearm to 950L tonearm is + $300. Over many years, what's +10%?

Difference? limits cartridge type? advice?

I decided to make an offer of $1,200 delivered for this old Denon with old but darn good motor TT81, long arm UA-7082, and a board with hole for a 9" arm.

I want Direct Drive, their Double Bi-Directional Servo is only on TT101; TT81; and TT71 motors

I'm thinking Stereo for  it's 12" arm, add 9" arm with Mono cartridge later, maybe Valentine's Day.

I have dusty forced air heat/cool, a dust cover is very important, a big dust cover for 2 arm setup is rare.

https://www.ebay.com/itm/VICTOR-CL-P2-TT-81-UA-7082-set-AC100V-Free-Shipping-d506/264532995172

IF Super 12 had a full dust cover, .... I could probably get a big one made for $200. by this guy

https://www.ebay.com/itm/Denon-DP-59L-New-JnB-Audio-Turntable-Dust-Cover-Made-in-USA/182380045189

Wish me luck.

We've been over this ground it seems like a thousand times, but I don't think all 3 of the Victor turntables you list have the "bi-directional servo".  The TT81 (according to hearsay) and the TT101 (according to my personal experience) are the ones to have.
On tonearm length, a 12-incher would in theory always be "better", geometrically speaking, but you need to factor in the cartridge compliance, the tonearm effective mass (which will always be greater for a 12-inch vs 9-inch version of the same tonearm design and construction), and your ability to set up the tonearm with precise accuracy, because an error in setting up a long tonearm will result in a greater final error in the geometry, compared to a similar error in setting up a 9-incher.  Further, longer tonearms might have greater problems with resonance, which will also affect SQ.  There is no good single answer to your question.