Tonearms that work well with better Koetsu stone body cartridges

Boxer, sorry for the late response. My comment focused on what other people hear, not what the individual hears for themselves. Of course what you hear is important but you can not trust what others hear even if you know them very well. You have to take everything with a grain of salt until you hear for yourself. Until you can hear for yourself you have to be able to evaluate designs based on their physical characteristics. This is particularly true for tonearms and turntables. You narrow it down to those designs you like best then try to audition them if you can. Most equipment I have to buy site unseen based on either overwhelming positive reviews like the JC1 amplifiers or by my own analysis of the design like the Schroder CB tonearm. I never got the chance to hear one before I bought it but given the brilliant design and the fact that Mark Dohmann uses it to demonstrate his Helix turntable added to the very reasonable price made it an easy purchase. I have not heard it yet as I am still WAITING for the turntable. If you have questions about tonearm design please feel free to ask.

Scott, The 4 Point is a brilliant arm. If you are setting it up yourself you will need a SmarTractor, a Hi Fi News Analog Test Record, and a set of Soundsmith graduated weight Cartridge screws. Once you have the tonearm dialed in with the SmarTractor you run the resonance tracks on the test record and find your resonance points. You add mass until you get the resonance frequency as close to 8 Hz as you can. Then sit back and enjoy. The 4 Point is a much more sophisticated design than the Ikeda. No competition there. Of course you can add mass to any arm as long as it has enough counter weight to balance it out. A Schroder LT with the heavy mounting plate would be another excellent choice if you can fit it on your table. The Stone Bodied cartridges are heavy so it won't take as much mass as you would think. That was the original idea behind the stone bodied cartridges, to make Koetsu's stiff design work in a wider variety of tonearms. Then it turned into "this stone sounds better than that stone," yada, yada. IMHO they all sound the same. So, get the color you like the best.

What people say they hear does not have much value. First of all with what speakers not to mention the rest of the system? What about his ears? I did a hearing test today on a fellow who complained of tinnitus. He thought his hearing was fine. It was steeply rolled off from 2000 Hz equally in both ears.
 Humans are terrible at describing what the heard. They can tell you immediately that they heard a violin but they can not tell you how the violin sounded. If they have been listening to a well balanced system problems with other systems problems will be obvious when they hear them. They can tell you it is too bright which is really brighter than what they have been listening to which if well balanced means they are right. 
A good tonearm should not have a sound of it's own like the Tri Planar, Schroder CB and Kuzma 4 Point 9. A good cartridge will sound exactly the same in all three arms. I can say the for the Windfeld Ti which I have heard in all three arms on a very well balanced system for what it's worth.   

The stone bodied Koetsus are very heavy so you can get away with lighter arms. The 4 Point is an excellent choice I think the 9" arm is the best of the lot. You should also look at the Reed 2G and the Schroder CB and LT. If your turntable can take it the Schroder LT is the best of the lot as it is a pivoted tangential arm. Reed makes the 5T, also a pivoted tangential arm but, it is animated and costs twice as much as the Shroder. Frank Schroder is a very clever guy.