From experience, I know that even the tiniest change in a setup parameter (e.g., .3 mm change in height of the arm) will make a substantial difference in sound. I would bet that if one set up two "identical" arms on "identical" tables with "identical" cartridges, one would get a quite different results -- either the sound would be different or setup parameters would be quite different to get matching sound. Therefore, I have serious doubts that someone can make side-by-side comparisons that are reliable.
What then should one rely on in making a choice? At best, I think one has to go with personal experience (if one hears a good setup, it must be the case that the particular arm, and any other component in the setup, is capable of good sound in the right setup). Also, a rough consensus from people that have heard a wide range of systems is helpful.
I went with the Vector arm because an audio distribution representative personally recommended the Basis arm and table even though he does not represent the products (he has heard literally hundreds of systems and has very good ears). I have managed to work my combination of arm, table (Vector Basis Debut vacuum), Lyra Titan cartridge, and Viva Fono phonostage) into a very good sounding rig, but, I bet I could have great results with all the other arms under consideration.
A friend with a Basis 2500 table with two arms (Vector and Phantom) HATES the Phantom arm (to him it sounds lifeless and dark) and much prefers the 2.2 arm that the Phantom replaced. I would bet that this is a setup issue myself; I intend to help him work out the problems.
I have heard all three arms in question myself in systems that were well sorted and liked the sound. I would bet that any would be workable. Among people I've talked to personally there tends to be more polarized opinions about the Phantom and and the SME than the Triplanar. If the Triplanar is not someone's absolute favorite, it is still up near the top. The same can also be said of the Vector arm.
