> Has anyone tried mounting, or booting from a Jaz disk? 

Yes, I boot from jaz.  Compile a lot etc.

> Is it any different than using a regular hard disk? 
No.  Just throw away all partitions that you are able to throw away.

> Is it possible to eject Jaz disks on the fly?
I'm not sure, right now the sytem is compiling binutils2.8,
but it works for cdrom after umount.
Just say eject /dev/<name>

> Do you have to do anything special to set a Jaz disk up?

No.

BTW, if you have a Daystar@50Mhz, could you do
a unix benchmark with/out the daystar?
Please look for Benoit Martels website
www.cs.mcgill.ca/~magus/benchmark.html

My colour classic gets 0.4 over-all, jaz vs hd does
not make a big difference.

Marc