I have a scoutmaster with the signature arm from elusive disk, which I originally bought with the Shelter 501.
The problem is that the cartridge is too light for the signature arm. With the counter weight pushed forward all the way, the maximum tracking force is 1.45 grams,
Most people say the shelter tracks best at 1.85 grams. I had to remove the fine tracking bolt in the back of the arm in order to increase the tracking force to 1.85 grams. It makes tuning the arm more difficult since you no longer have fine-tuning capabilities.
My opinion: the cartridge should not be sold with the signature tonearm unless it includes the 3 gram headshell weight.
The Shelter sounds better once you increase the vertical tracking force. Setting the azimuth properly is also critical for getting it to track right. I got to where it sounded sweet, but was unable to get rid of a lot of noise. Since I decided to upgrade to the 10.5i arm and higher-end dynavector cartridge, I gave up on setting the cartridge up correctly, which takes a lot of time. So I cant really tell you how good it can sound.
I hope this helps.