One of my groups sent this out today.
"1) Yes, Emerald will be banned as of 10am SLT today.
2) Emergence and Phoenix are both Emerald clones that have been cleaned up. They are slightly different because they are based on different versions of the Emerald code. Phoenix is the more advanced one. Phoenix, however, shares a bug with Impudence in that some textures won't render correctly due to probs with th jpeg2000 libs. Neither Emergence nor the SL standard viewer have this problem.
3) Emergence is a stopgap. The developer, LordGregGreg joined the Phoenix team.
4) Different viewers have different strengths. There is no one "best" viewer.
5) If you keep crashing when you try a new viewer - here is a likely cause. Sometimes different viewers don't like sharing the same texture cache with other viewers. Just clear your cache before trying a new viewer. Better still, if you know how to do it, create seperate designated texture and sound caches for each viewer you try (under Prefs/Network/Disk Cache Location"
As a side note I saw there is a Phoenix add on now for crashers. It seemed to help me. I have tried many different viewers now and really can't vouch for any, but am on Phoenix at the moment.