Shawn,

with the database of this size
you might evenconsider splitting it on two TSM instances.
There are advantages and drawbacks coupled with that,
but it works.

>> - Migrate all the client nodes one by one to other machines with
>> import/export. 
I did it when I moved from OS/2 to NT Server,
and it worked flawelesly.
It is even easier if you have either enough tape ressources,
or you can afford temporarily disk space to export/import single clients.

regards
Juraj salak