Dumb filesystem idea

[Indigo]

Hello Everyone,
  Im about to try a disklayout experiment and I wanted to ask everyone if  
Im trying things that are pointless or if I should extend the experiment  
somehow.

Hardware:
  Highpoint RocketRAID 2320
  2xWD Raptor 74GB
  5xWD Caviar 320GB

Original idea for the setup:
  74GB RAID1 (Raptors)
   /,/var,/usr
  50GB RAID0 (Caviars[10GB from each - maybe less])
   swap,/usr/obj,/tmp,[/var/audit]
  1TB+ RAID5 (Caviars[the rest])
   /home (or just general storage)

The goal is to waste as few fast/reliable space as possible on things that  
CAN be lost and to generally reorganize the filesystem by file purpose.

Known issue is that I'll need some script to recreate the RAID0  
filesystems when they crash.

Am I onto something here? I feel like running in circles - it's dumb to  
put /var/obj on the RAID1 where it just eats valuable space. But it's also  
dumb to put things on a RAID0 where they will crash a running system in  
the event of disk failure. I know my idea won't work but I wanted to ask  
if anyone was playing with similar ideas.

Thanks,
Vasek