Rereading the thread:
Thanks Stingreen - I very much appreciate your contributions, and will do a new check. So far, however, the azimuth seems ok. Like Mmakshak commented above, it can be hard to judge, what is the cartridge, what is the speaker positioning, and so on - you need to sleep on it, and use your subconscious to get the whole system fully tuned to the room. This is an endless task. Happily it is also filled with joy - just listen to the music!
Ninetynine - the SME arm should be heavier, to be optimal for the Atlas. I am not sure. I tried some damping/heavier stuff but went back to the original. As often happens when I try to tweak the SME V.
Nandric - stylus shape is important - I did not get how this would translate to anti-skate and weight.
Some of the debate turned to mistracking - although not the main issue in my case. It seems that most users, including me, thinks the Atlas sounds great and seldom mistracks. As stated before, this thread is about getting optimal sound.
Raul has argued that the Atlas needs a solid state (or hybrid) phono preamp / riaa solution to sound its best. Too many tubes will not do. The debate - here as elsewhere - has turned to solid state vs. tubes. I agree that phono preamps are not the main subject of this thread, but a little discussion will not hurt. After all, the phono is a main part of making the cartridge sound good. But we should restrict this to phono stages actually listened to using the Atlas. Raul, have you heard solid state phono stages that serve the Atlas in a superior way?
All in all, with 3851 views on Audiogon and 98 posts so far (one of them calling our discussion "erudite"), I think the thread has been succesful. The group of Atlas owners / users is fairly small, but our discoveries and debates have a more general interest. Each of us are likely to be sometimes wrong, but together, we may be right. So I look forward to more comments.