Cdk84I arrived at the same conclusion after my tests.
I ought to have mentioned, for several reasons, that I've had considerable listening time with Both SME V-spec arms, the 9" and the 12. The difference is Very Pronounced. This is direct experience with at least 200 hours' listening.
Cdk84
From another pretty reliable source I've heard comparison of the 312-S and V-12; if their report is as trustworthy as I suspect, there is no comparison between the arms, just as there is very little shared between the V-9 and V-12. The SME V-12 arm, properly set up --which takes some time, patience and developing expertise-- gives some of the finest playback I've heard, ever.
I too did this comparison, both arms mounted on the same table using two identical Air Tight Supreme cartridges and identical high quality tonearm cable.
I also ran the SME 312S against the Kuzma 4 Point, Micro Seiki MAX, Talea II, Audiocraft AC4400, Technics EPA 100, Graham Phantom 12" and Primary Control 10.5" and Primary Control 12" tonearms.
All these arms have a personality, none are perfect including the one I choose to keep. Beyond arm choice is set up, which can easily undo whatever gain one arm design or material might have had over another.
Tracking force variation of 1/100 of a gram can alter the sound, especially a high performance cartridge like the Lyra Atlas or Air Tight Supreme.
I did not do any of these tests with Benz except SME 312S versus Primary Control 10.5 and in that case the tonearm cables were not identical, basically tilting the test.
Which arm is the winner is going to depend on what you like, assuming each is performing to it's maximum. If I had to rate this cluster of arms I would put SME V-12 at the top and Kuzma 4Point close behind.
The next tonearm in line would be a tie between Graham Phantom 12' and rewired (silver) Micro Seiki MAX 12" with Titanium wand.
Results could vary a lot depending on turntable mat, isolation of your turntable and if you use a record weight (or clamp) and which brand.
Last, if you choose SME you must use an aftermarket protractor such as MINT brand and inform them before hand which cartridge you plan to use and what the cantilever length is. This because SME relies on an industry standard that is not always followed, so setting up blindly using their instructions can make the tonearm to spindle length wrong. This because SME mount requires user to MOVE the mount position to accommodate stylus over the template.
Cdk84
I listened last night to a range of familiar source material with the SME V-12 and found myself referring to Fremer's review and the viewpoint of one of the above-mentioned listeners. Essentially they say the Kuzma 4PT is more 'lively' than the SME V-12. When I listened last night I asked whether anything more 'lively' sounding could possibly be other than exaggeration, as the SME V-12 was so solid, so credible, so well balanced, feeling accurate both timbrally and in wealth of textural detail. It tamed the sibilance on 'April in Paris', gave better depth and color to the skins, more air to the cymbals on the Sheffield Drum Track while still representing the flaw of the recording, namely that the drum kit sounds almost twice life size (ie: gives more of the good stuff without lying about the liabilities). How could something be more real?
You may have answered your own question with that statement. What you describe is the "rock solid" sound of the Magnesium SME design and it's close tolerance bearings. Add to that, rubbing your fingers along the headshell or tonearm wand will not generate noise into the speaker. Many tonearms get very excited by any movement including room vibration, sound pressure level and of course the LP itself.
If one prefers any excitement the specific arm / cartridge combination if providing then moving to another will be a disappointment. For that reason there are many "winner" tonearm and cartridge combinations and it's impossible for anyone to state with 100% accuracy what is the best.