I have some new information regarding the Longhorn Gold1 and Green1. My friends at Grado Labs has supplied me with the following bit of information. Both Grado cartridges have a dynamic compliance rating of 20. This is a specification that is not normally published, but may help some of those ridding the fence on deciding whether to buy or not (regardless if it's a Longhorn or regular Grado). A plain Grado weighs 6 grams and a Longhorned version, 7.5 grams.
This make almost all arms compatible with the cartridge, that are in the 10 to 25 gram range. The 10 gram arm is a little light, with the resonance frequency approaching 12 hz, while the heavier arms will put the resonance frequency at about 7 hz. Clearly, the acceptable window is between 5.5 hz and 14.5. The ideal arm would be about 15-20 grams.
To determine your arm's weight, you really need to have a digital scale that will go up to about 30-40 grams. Step one is to remove the counter weight. This puts all of the arm's weight on the head end. If you do this with a cartridge installed, you'll need to protect the stylus, or remove the cartridge all together to prevent stylus damage. Simply put the end of the tonearm on the scale and read the weight (in grams). If you have a cartridge installed, simply subtract the weight of the cartridge from the total weight to capture the arm weight alone.
This technique does not mean that the cart will track perfectly, but at least you will know that the inherent resonance frequencies will be in the correct range.
Wayner