All else being equal, a 12" inch arm should be better than a 9" arm (who can argue with more inches is better, guys?). The trouble is, there is no way to make all else equal.
it is a matter of designers making their choice of tradeoffs. But, to say that one aspect of design, specifically length, is so important that a long arm is inherently superior, as someone mentioned that Roy Gregory has suggested, I don't buy.
Larryi- you nailed it. All designs are compromises. Even "cost no object" designs. As Larry says, a longer arm is always heavier, all else being equal. We can change the arm tube material, or wall thickness,etc., , but then its not the same as the shorter arm.
Zieman- your posts are entertaining, but you don't seem to be able to actually carefully read others. The whole disc/drum analogy is that, (with the exception of truly breakthrough technologies), implementation of any design is usually more important. And I would truly prefer to have a well executed mature design than a first gen more advanced design with flaws and/or low cost materials. Perhaps that's part of the reason why Guarinis and Strativerii (sp?) fetch "a bit" more than current Yamaha violins. Newer sometimes is better, but not always. Non-quantitative (= design execution) factors may be more important in artistic (=music) endeavors than quantitative (= SOTA design) factors.
And of course with vinyl playback, there are so many interactive components involved, I think I fall in Raul's camp...Not on shorter is better (insert your own filthy leering comment here) but on, and I am paraphrasing, its the system. A tone arm/cart/TT/phonostage is a system that can be optimized, but I'm not so sure any one component can be optomized in isolation. My $0.02. YMMV, and if id does, then so be it.
BTW, I would suggest canning the xenophobic remarks. This forum benefits from viewpoints from all cultures.