I use my Koetsu for string quartets and the like not for R+R and rarely for Jazz. The other cartridges I use are more neutral and to my ear more accurate not to mention better trackers (more accurate is not equal to better sounding.)
mulveling, I certainly can not argue with your opinion. The FR's are certainly heavier arms. I would never use a Koetsu in a uni pivot arm. Actually, I would never use anything in a uni pivot arm so I guess that is not saying much.