I just installed 3.1. I am one of those guys that really like A3 because of it GUI and simplicity. The program is quite slow and mobileme is at best "dodgy" but I use em both 
But i use a new a3 library per client and sometimes if the client is big his different jobs get a different library as well - just makes it faster for me to work.
However updating to 3.1 in typical Apple fashion it kept all settings except - manual control of the mobile me gallery, so my machine has just started syncing 40+ galleries and about 15gb of info...... All into one of my libraries... Thanks Steve,
Thing is that you cant quit the process because the galleries gets "f..ed" up.....
