suggestions for postgresql setup on Dell 2950 , PERC6i controller

Hi,

I am going to get a Dell 2950 with PERC6i with
8 * 73 15K SAS drives +
300 GB EMC SATA SAN STORAGE,

I seek suggestions from users sharing their experience with
similar hardware if any. I have following specific concerns.

1. On list i read that RAID10 function in PERC5 is not really
striping but spanning and does not give performance boost
is it still true in case of PERC6i ?

2. I am planning for RAID10 array of 8 drives for entrire database
( including pg_xlog) , the controller has a write back cache (256MB)
is it a good idea ?
or is it better to have 6 drives in HW RAID1 and RAID0 of 3 mirrors
in s/w and leave 2 drives (raid1) for OS ?

3. Is there any preferred Stripe Size for RAID0 for postgresql usage ?

4. Although i would benchmark (with bonnie++) how would the EMC
SATA SAN storage compare with locally attached SAS storage for the
purpose of hosting the data , i am hiring the storage primarily for
storing base base backups and log archives for PITR implementation.
as retal of separate machine was higher than SATA SAN.

Regds
mallah.