Performance of 2780 controller and 141GB drives

Any experience with consolidating DASD on the new 141GB drives out there? 

On the new box we are ordering it has been suggested that we move from
a RAID environment to a mirrored environment. However, to be
affordable, this would mean consolidating the data storage onto fewer
drives. Being from the old school of "small drives and lots of arms",
I am skeptical of the performance of this configuration.

The current configuration on our 730 consists of two RAID sets, one
with 20 8GB 10K drives and the other with 16 17GB 10K drives. This
gives ~400GB on 36 arms. The proposed configuration for the i5 520 is
for mirroring at the IOP level using the fast 2780 controllers with  a
total of 16 141GB drives plus 2 35GB drives as mirrored load source in
the CEC. This gives ~1TB of usable data storage.

Any opinions? Suggestions?

Kind regards,

Brian