In the post above to Adam, Nick you mention that the improvements come from 64bit. I'm still not sure why the move away from SIS in the message body and for future. It's implied that it's done for performance, but as you mention above the performance primarily comes from 64bit and other areas.
I also don't understand the direction from MS to create so many Storage Groups and keep a single database within them. That TOTALLY removes SIS and increases the number of tracking log files and disk space on Exchange servers. And in my experience, reduces performance. Multiple databases I can see (in large organizations), though I tend to use them to keep big mailboxes (exceptions) from the normal users.
Can you elaborate more on why the move away from SIS?
Thanks!!