Raul, With all due respect, you are wrong about the SME bearings and wiring. As Riccardo Muti said, " CON ME, NO!" A very good friend of mine was a close associate of the late Alastair Roberson-Aikman, the founder of SME. As such he has intimate knowledge of the SME products and their technology. He owns an SME 30 with V arm and an SME 30/12 with V-12 arm. He has had the 30 for 19 years. He told me this morning that the bearings in the V-series arms changed about ten years ago, and today, the bearings in the standard V and the V-12 arms are the exact same. The internal wire in the V series changed also around that time and today, the current V and V-12 arms have the same internal wiring. My SME V and V-12 are both current models, though I just sold the former. Of course the arm wand is longer and therefore different, and this is accounted for by the greater effective mass.
I can not tell you what is responsible for the difference in sound that I heard between the V and the V-12, but geometry would seem to be the biggest change. The position of the counterweight is closer to the pivot on the V-12, so that reduction in the moment of inertia may play a role. What I hear is less distortion, a cleaner, smoother sound, larger soundstage, slightly greater frequency extension and an overall more realistic presentation. This was confirmed by some friends who also heard the comparison. The SME site does claim a 27% reduction in tracking error with the longer arm, though this is I think based on the SME 312S arm.
I don't know of other 9" and 12" arms from the same manufacturer that are so similar to each other as the SME V series arms are, though there may be some. I think that directly comparing these arms and hearing the results speak for themselves. We can each decide for ourselves. Over time the audiophile community will see if the current popularity of the 12" arms are simply a fad as you suggest.
Are you sure your Sony PUA-237 will outperform the V-12? I don't think either of us has actually heard that comparison, so I will not make any such claims. I also will not make any claims about other 12" arms that I have not heard. I think a few Audiogon members are getting ready to compare the new 12" Triplanar, 12" Phantom Elite and SME V12. That should make for some interesting listening and discussion.