Linn LP12 vs Thoren TD350

I currently own a nice Linn LP12 with lingo powersupply, a Naim Aro tonearm and a built in Naim phono/pre with hicap power supply. In the opinion of the analog nuts out there, would a Thorens TD 350 with an SME M2 tonearm be an upgrade, a downgrade, lateral or just good but differnt. Going to the Thorens would also require the purchase of a new phono pre.

Rest of system ins C-j, Marantz and B&W. Music taste is varied from Andy Williams to country to Led Zep.

I am satisfied with the sound of my system, but like many, get restless.

Thanks for your input.
I think it would not be an upgrade. It might be TD550. I had moved from Rega P3 to TD350 (with TP 250 tonearm and Benz ACE H) but I was not satisfied. When I changed TP 250 with Kuzma's Stogi ref, the sound improved appreciably. Now I have in mind to change cartridge Benz ACE with Benz LP. I have not heard LP12 but it is a "legend" judging by reviews. Both LP12 and TD 350 have the same construction, namely sub-chassis. LP12 can be upgraded with better arm and/or cartridge and better phono pre (see adjacent thread). Good lack!
A downgrade, no question.
I would stay with the LP12 and look at investing in upgrades to it. Such as Cirkus bearing, trampoline, keel etc. Even a dealer tune up can do wonders if it hasn't been done in a while. I have a LP12 and a year ago wanted to "upgrade" or get something new. After looking at different tables, I still have and LP12 and am saving for a new cart and maybe a keel down the road. Also Linn just introduced new power supply and phone pre-amps that sound extra awesome. But they cost lots of $$$$
You need a change! I went through the entire Linn upgrade, after about 10 years and 10Gs I still wasn't really satisfied. I went backwards.. big time. I bought an old Dual 1229 idler drive table, rebuilt the motor and bearing, remove all of the auto start hardware including the arm and installed a NOS Grace 747 with a Denon 103. WOW! is all I can say. Bass slam like I never experienced, solo piano is like I am THERE.. etc, etc. Why not try a Thorens 124, or a Garrard 301? These too have the idler drive system, and changing, installing arms is much easier. Personally, the Thorens would be my vote, as the Garrard can be tedious though rewarding when set up. Oh, and I lost my shirt when I sold my Linn, they are worth almost nothing these days which is a heart breaker. You may just want to keep it around for comparison sake. Try a well made, well engineered idler driven table, you'll smile every time you play a record. Mine runs every single day for years now, and I still can't believe how good it sounds. Best.
Linn LP12 is great but it has so many different modifications and upgrades so it`s really hard to judge.