Although I do agree with others here that the stylus and cartridge maybe more important than the tone arm WHEN mechanically reproducing sound from vinyl.@tyray Dave Slagle recently sent an article to me by Peter Moncreif, who did some testing on cartridges and how they make distortion. It was an interesting read! I found it interesting that while he was able to show that the cartridges did seem to make distortion, he really didn't go into much about the arm despite testing a good number of cartridges. Yet no mention of the arm, but we all know that getting the cartridge/arm combination to work its mechanical resonance has to be in the 7-12Hz range, and otherwise how tiny little tweaks in the adjustment can have a huge affect on the result!
It obvious to me that if there is an adjustment on an arm that is tricky to set up, the chances of getting it correct are vastly reduced. We've all heard cartridges make distortion; if you can set all the parameters right, then its clear that distortion is reduced. I've seen arms that don't allow for adjusting the VTA, others that allow you to adjust it, but only by loosening a screw and moving the entire arm (the old Grace is an example of this); many have no adjustment for azimuth whatsoever... To put this to an extreme to make my point, you can't expect to put a $5000 cartridge in a Voice of Music tonearm (google images...) and expect it to work properly! So at what point do you draw the line? What I've found is that the arm is more important if you really want to get things right- so that is where I make that distinction.