They're both good cartridges, but I like the Shelter better overall. On the Space arm, I have received several communications from qualified users who have gotten good results with the 501 on it. I don't think you have to worry about that with this arm and the 501.
For the Shelter 501, load at about 100 ohms(or thereabouts), and use your highest gain setting.
VTA should be very slightly negative.
Tracking force is good around 1.8- 1.9g, and is pretty sensitive to small changes. Some experimentation with 1/10 gram changes may give noticeable improvements.
Break-in takes about 40 hours, and it goes through some unusual stages in sound during this time. Don't judge the cartridge early, it will be great after break in.